IB Biology A3.1 Diversity of Organisms

Summary

This script delves into the diversity of life, discussing the distinctions between prokaryotes and eukaryotes, and the fundamental characteristics of living organisms. It explores the importance of genetic variation for survival and natural selection. The script also covers Carl Linnaeus's binomial nomenclature, the biological species concept, and the challenges in defining species, such as hybrids like mules and ligers. It touches on DNA's role in organism development, chromosome analysis, genetic diversity, and the implications of genome sequencing for understanding evolution, fighting diseases, and advancing personalized medicine. The script concludes with the creation of a dichotomous key and the innovative applications of DNA barcoding in species identification.

Takeaways

• 🌐 The Earth hosts a vast diversity of living organisms, with estimates ranging from 3 to 100 million different species.
• 🔬 Genetic variation within and among species is crucial for the survival of life, particularly through natural selection.
• 📚 In the 17th century, species began to be named systematically, and in the 18th century, Carl Linnaeus established the binomial nomenclature for consistent species naming.
• 🔑 The binomial nomenclature assigns each species a two-part scientific name: the first part is the genus, and the second is the species, both derived from Latin and written in italics.
• 🤔 The biological species concept defines a species as a group of organisms that can interbreed and produce fertile offspring, sharing a common gene pool.
• 🚫 Some organisms, like mules and ligers, do not fit the biological species concept because they are sterile and cannot reproduce fertile offspring.
• 🧬 DNA evidence has become instrumental in distinguishing populations and species, especially when traditional physical characteristics are not definitive.
• 🧬 Humans (Homo sapiens) have 46 chromosomes, which is close to chimpanzees, highlighting our genetic similarity despite differences in chromosome numbers.
• 🌱 Plants often have a higher tolerance for chromosome mutations, resulting in a wider variety of chromosome numbers compared to animals.
• 🧬 Genetic diversity arises from processes like crossing over during meiosis, which shuffles genes and contributes to the variation within a species.
• 🌐 Genome sequencing has revolutionized species comparison and classification, with the cost dropping dramatically from $100 million to about $1,000, enabling broader applications in science.

Q & A

What is the estimated range of different species living on Earth according to the National Wildlife Federation?

The National Wildlife Federation estimates that there are three to 100 million different species living on Earth.

What is the importance of genetic variation within and among species?

Genetic variation is essential to the survival of life, particularly through natural selection, as it allows species to adapt to changing environments and maintain their existence.

Who is credited with establishing the binomial nomenclature system for naming species?

Carl Linnaeus is the primary scientist credited with establishing the binomial nomenclature system for naming species.

What are the two parts of a species' scientific name and how are they written?

A species' scientific name consists of two parts: the genus (first word, capitalized) and the species (second word, lowercase). Both words are written in italics when typed or underlined when handwritten.

What is the defining feature of a species according to the biological species concept?

The defining feature of a species is the ability to reproduce and have surviving and fertile offspring, sharing a common gene pool.

Why are mules and ligers not considered their own species despite being hybrid organisms?

Mules and ligers are not considered their own species because they are sterile and unable to reproduce and have their own fertile offspring.

How does the process of natural selection contribute to the diversity of species?

Natural selection contributes to the diversity of species by favoring certain genetic traits that enhance survival and reproduction in specific environments, leading to gradual changes and speciation over time.

What is the significance of the number of chromosomes in a species for its reproduction?

The number of chromosomes in a species is significant for reproduction because it ensures that gametes (sperm and egg cells) have the correct number of chromosomes to form a viable zygote with paired chromosomes.

What is meant by the term 'genome' and how does it relate to species diversity?

The term 'genome' refers to all the DNA, including all the genetic information of an individual. The genome sequence, including the number of base pairs and gene sequences, contributes to the diversity of species by encoding the characteristics that allow for adaptation and survival.

How does the process of crossing over during meiosis contribute to genetic diversity within a species?

Crossing over during meiosis contributes to genetic diversity by exchanging segments of chromosomes between homologous chromosomes, creating new combinations of genes in the offspring.

What is DNA barcoding and how is it used to identify species?

DNA barcoding is a technique used to identify species from small samples of DNA by comparing specific gene regions, such as the cytochrome C oxidase subunit I (Cox1) gene in animals, to a database of known sequences.

Outlines

00:00

🌿 Diversity of Life and Species Classification

The script begins by discussing the diversity of life, emphasizing the vast number of species on Earth as estimated by the National Wildlife Federation, which ranges from 3 to 100 million. It underscores the importance of biodiversity for the planet's ecosystems and the process of natural selection. The video then delves into the historical development of species naming, starting with Carl Linnaeus's binomial nomenclature in the 18th century. This system categorizes species into a hierarchical structure from domain to species, with each species having a two-part Latin name. The script also introduces the concept of the biological species, which are groups of organisms capable of interbreeding to produce fertile offspring. Exceptions to this concept, such as mules and ligers, which are sterile hybrids, are also mentioned.

05:00

🧬 DNA's Role in Species Identification and Hybrid Challenges

Paragraph 2 talks about the role of DNA in distinguishing species and the challenges posed by hybrids that don't fit the traditional biological species concept. It explains how populations, which are groups of the same species in the same area, can diverge genetically over time due to different environmental conditions, making species identification complex. The paragraph also discusses how DNA evidence aids in species identification and the significance of chromosomes in determining species. It mentions that most species have an even number of chromosomes due to sexual reproduction, with humans having 46 chromosomes. It also touches on the differences in chromosome numbers between humans and chimpanzees, highlighting the genetic similarity between the two species.

10:02

🧬 Unity and Diversity in the Genome

Paragraph 3 explores the unity and diversity within the genome, which is the complete set of genetic information for a species. It explains that members of a species share the same DNA and genes, although the sequences might vary slightly. The concept of crossing over during meiosis, which contributes to genetic diversity, is introduced. The paragraph also discusses genetic variation, specifically alleles and single nucleotide polymorphisms (SNPs), which are sources of diversity within a species. It mentions that while there is a significant amount of unity in the DNA among species, diversity is observed in the actual gene sequences and the number of base pairs.

15:05

🌐 Genome Variation and Species Diversity

Paragraph 4 discusses the variation in genome size and the concept of nonfunctional DNA, sometimes referred to as 'junk DNA,' which makes up about half of the human genome. It highlights the importance of comparing base sequences to understand the evolutionary relationships between species. The paragraph also addresses the challenges in defining species, especially when considering asexual reproduction and horizontal gene transfer in bacteria, which can complicate the application of the biological species concept. It emphasizes the importance of chromosome numbers being the same within a species for viable and fertile offspring.

20:08

🧬 Chromosome Consistency and Genetic Disorders

Paragraph 5 focuses on the importance of consistent chromosome numbers within a species for successful reproduction and the avoidance of genetic disorders. It explains that while the number of chromosomes can differ between species, they should be consistent within a species for fertility and viability. The paragraph also discusses the process of meiosis, which ensures that gametes have the same number of chromosomes, and how genetic disorders like Down syndrome can occur due to extra or missing chromosomes. Additionally, it touches on the concept of a dichotomous key for identifying species and the application of DNA barcoding for species identification from environmental DNA samples.

25:09

🔍 DNA Barcoding: A Tool for Species Identification

The final paragraph introduces DNA barcoding as a method for identifying species from small DNA samples found in various environments. It explains how this technique can be used in forensic science, food safety, ecological assessments, and the detection of invasive species. The paragraph highlights the wide range of applications for DNA barcoding and how it has become a valuable tool for scientists and biologists in species identification and environmental monitoring.

Keywords

💡Species Diversity

Species diversity refers to the variety of different species that exist within a given ecosystem or on the planet as a whole. The video emphasizes the vast array of life forms, estimated to be between three to 100 million species, highlighting the importance of this diversity for the planet's ecological balance and human existence. The concept is foundational to the video's theme, as it sets the stage for discussing how biodiversity is maintained and studied.

💡Genetic Variation

Genetic variation is the difference in DNA sequences among individuals within a species or between different species. It is crucial for the survival of life, particularly through natural selection, as it allows species to adapt to changing environments. The script mentions genetic variation as essential for life's survival, indicating its role in the video's narrative about the mechanisms that drive biodiversity and evolution.

💡Carl Linnaeus

Carl Linnaeus was an 18th-century scientist known for establishing the binomial nomenclature, a system for naming species. His work is highlighted in the video as a pivotal moment in the history of biological classification, showing how species are given two specific names reflecting their genus and species identity. Linnaeus's system is integral to the video's discussion on how scientists categorize and name species.

💡Binomial Nomenclature

Binomial nomenclature is a naming system for species, where each species has a two-part name consisting of its genus and specific epithet. The video explains that this system, developed by Carl Linnaeus, provides a universal language for scientists to communicate about species. It is exemplified in the script by mentioning 'Homo sapiens', where 'Homo' is the genus and 'sapiens' is the species.

💡Biological Species Concept

The Biological Species Concept defines a species as a group of organisms that can interbreed and produce fertile offspring. The video uses this concept to explain what constitutes a species and why it matters for reproduction and gene pool sharing. However, the script also points out its limitations, such as in cases of hybrids like mules and ligers, which complicate the application of this concept.

💡Hybrids

Hybrids, such as mules (a cross between a horse and a donkey) and ligers (a cross between a lion and a tiger), are mentioned in the video to illustrate exceptions to the Biological Species Concept. These organisms, while they can exist, are typically sterile and cannot reproduce, challenging the traditional definition of a species. The inclusion of hybrids in the script underscores the complexities in classifying and understanding species boundaries.

💡DNA Sequencing

DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. The video script discusses how advances in DNA sequencing have revolutionized species identification and classification. It allows scientists to compare species at a genetic level, which is crucial for understanding evolutionary relationships and genetic diversity.

💡Chromosomes

Chromosomes are structures within cells that contain DNA and carry genetic information. The video explains that each species typically has a specific number of chromosomes, which can be used to distinguish between species. The concept is used to discuss how genetic material is organized and passed on, and how variations in chromosome numbers can lead to species differences or disorders like Down syndrome.

💡Genome

A genome is an organism's complete set of genetic information. The script discusses how the study of genomes, including the comparison of genome sequences, provides insights into species' evolutionary history, genetic diversity, and potential for adaptation. The human genome project is mentioned as a landmark achievement in sequencing an entire genome.

💡DNA Barcode

DNA barcoding is a technique mentioned in the video that uses a short DNA sequence from a standard region of an organism's genome to identify species. This method is highlighted as a modern application of genetic knowledge, useful in various fields such as forensic science, ecological assessments, and food safety. It exemplifies how genetic information can be applied to identify and classify species in the wild.

Highlights

The National Wildlife Federation estimates 3 to 100 million different species live on Earth.

New species are discovered and go extinct constantly.

Genetic variation within and among species is essential for survival.

Carl Linnaeus established the binomial nomenclature for naming species.

Species are categorized from domain to species in an upside-down triangle system.

Species have a scientific name with a capital genus and lowercase species name.

The biological species concept defines species as groups capable of interbreeding.

Hybrids like mules and ligers challenge the biological species concept.

Populations are groups of the same species in the same area at the same time.

DNA evidence helps distinguish populations and species.

Chromosomes are essential for species persistence, typically in even numbers.

Humans have 46 chromosomes, receiving 23 from each parent.

Chimpanzees, with 48 chromosomes, are genetically very similar to humans.

Plants have the most chromosomes due to their ability to tolerate mutations.

Karyotypes organize chromosomes by size, banding patterns, and centromere position.

Genomes consist of all an individual's DNA, with genes determining protein production.

Crossing over during meiosis leads to genetic diversity.

Alleles are alternate forms of a gene, often differing by a single nucleotide.

SNPs (single nucleotide polymorphisms) contribute to human diversity.

There is more genetic diversity between than within species.

Genome sequencing has become faster and cheaper, enabling species comparison.

Genome sequencing helps trace human migration, genetic diseases, and health.

DNA barcoding identifies species from small DNA samples.

The biological species concept faces challenges with asexual reproduction and horizontal gene transfer.

Transcripts

now that we've had time to discuss the

differences between procaryotes and ukar

as well as the overall characteristics

of living things in general we want to

turn our attention to what makes living

organisms different what is the

diversity of organisms and this is for

IB section a 3.1 on our planet there is

a wide diversity of living organisms the

National Wildlife Federation estimates

that there are three to 100 million

different species that live on the

planet which is really just astounding

regardless of where we're actually at in

that scale new species are being

discovered all the time and

unfortunately species are also going

extinct all of the time that variation

of life is essential to our existence on

the planet and to Life's existence on

the planet uh both within differences

between species and differences among

different species um and there's a wide

variety of of different types of species

on the planet as we see in some of these

pictures here genetic variation or

differen is within uh species and

amongst different species is really

essential to the survival of life and

particularly the survival of um life

through natural selection and so in this

video we're going to be examining how

are those differences um what are those

differences in in our variation of life

so today all species have a scientific

name and as humans we really like to

categorize things and so uh in the 17th

century this began to become a trend

where species that were discovered began

to be named and without some

organization uh there wasn't consistency

in in how different species were named

and so in the 18th century Carl anaus is

the uh primary scientist that began to

establish a naming system uh and he used

the morphology of an organism the

internal and the external structures to

help describe an organism as a species

and then species are groups that have or

had at the time similar traits today we

use uh and can use DNA sequen would seem

to be able to distinguish one species

from another but at the time it was

primarily based off of internal and

external structures uh and so Carl and

as developed what we now know as the

binomial nomenclature in which species

have two specific names and species are

divided um uh through a categorizing

system with the most broad being the

domain and then becoming more and more

specific as we see in our upside down

triangle where we start with the main

and then progress to Kingdom f class

order family genus and then species and

as we move down that list the

similarities between group um species

within those groups becomes more and

more specific and so how a species is

named it consists of two parts typically

it's of Latin Origins the first word in

a species name is always capital and it

designate the species genus the second

word in a species name is always

lowercase and this is the actual species

names and so for humans it would be Homo

sapiens where homo is the genus and

sapiens would then be the species uh

both of these words are always written

in italics if it's typed out or if it's

handwritten it would be underlined and

when we're using this in a text after

the first use um or or or writing of of

the species name it can be abbreviated

so that it's just the initial letter of

the genus and then the the species name

so H sapiens for homo sapiens and so

this is now how we name species so that

there is some consistency and it's used

worldwide by all scientists so

scientists in different parts of the

world can refer to the same species and

be clear about what they're actually

talking about so our next question then

is what defines or makes a species and a

biolog biological species is referred to

uh as the biological species concept

where this concept is the idea that a

species is an unchanging group of

organisms with differences both internal

and external from other species and and

as we'll get into a little bit later on

in the course species do change we we

know this through natural selection

because of changing environments um but

at any one point in time we can still

apply this as an unchanging group uh of

species in which the species the

organisms within that species are all

capable of breeding and have surviving

reproducing Offspring and that really is

the defining feature of what makes a

species is the ability to reproduce and

have surviving and fertile offspring so

that they can actually produce uh

species also share a gene pool and this

concept this idea works well for most

species but not for all uh sometimes

it's possible that species can intermix

and uh produce Offspring uh probably a

most common example of this would be a

mule uh which maybe you're familiar with

cross of a horse and a donkey produces a

a mule uh a living organism is it a

species it's kind of an interesting

question um scientists would generally

say no

it's not its own species because that

mule is sterile it's not able to

reproduce and uh a little bit more fun

example would be a liger which cross

between a lion and a tiger and

additionally the liger generally most

often are also sterile uh and so these

hybrids a mule or a liger while they do

exist as organisms it doesn't really fit

this uh biological species concept idea

in that an offspring is produced but

they're not fertile so they're not able

to reproduce and have their own

offspring that are fertile and so these

hybrids which also occur in Plants the

genus alium contains hundreds of species

onion and garlic in which the hybrids do

exist in natural habitats uh and so

sometimes most times this concept of of

what makes a biological species is

applicable to most species but not

always because of these hybrids uh we

don't see liers run around in the wild

because the lion and the tiger habitat

don't overlap mules we see in captivity

as well as ligers primarily in zoos and

so the idea of what makes a species fits

for most but not for everything and it

kind of goes back to this idea that

there's always kind of some exceptions

within biology uh Concepts or or rules

then based on this idea of a biological

species concept it is challenging to

distinguish populations and species from

one another uh what makes a population

is a group of organisms of the same

species in the same area at the same

same time and regardless of distance if

groups are genetically similar if we

look at their DNA and they're

genetically similar they are the same

species but separated species can

diverge over time and this is because

the environments that they're in may be

different and this can cause a group of

organisms a population within an area to

to change over time through natural

selection and they may develop

differences uh this would be a gradual

process and so it it makes it difficult

to determine whether populations are dis

distinct species or if they are the same

species and then what how much of a

difference must be present in order to

distinguish different species and so

this makes defining species difficult uh

and and it's a challenge and is easier

now that we're able to examine DNA

evidence to to help make some of those

decisions a good example of this we can

see with lions throughout Africa there

are different lion populations spread

throughout the continent they're the

same species Panther a Leo but they can

experience uh gradual changes due to the

specific environmental conditions of

where they're at and so those in Eastern

Africa might experience some um much

different environmental conditions

though than those that would be in South

Africa or western Africa and so that

makes it difficult to distinguish are

they different species or are they the

same species with slight variations in

their DNA and the general consensus

would be that they are all of the same

species currently on the on Africa we

have previously discussed how DNA is

essential for the development of

organisms and is responsible for all the

characteristics of an individual

organism and as for species for that

matter DNA typically is found within the

nucleus for eukaryotic cell organisms

and is contained within the nucleus and

is long wispy strand uh that's difficult

to organize as that cell begins to

prepare for duplicating uh for dividing

through mitosis the DNA condenses down

into chromosomes and we can look at

chromosomes and compare between

different species and when we do so we

see that each species typically um not

typically does have a different number

of chromosomes um and it's it's possible

that those number of chromosomes can

change uh throughout the ex existence of

the species though that would occur over

a very long per time periods and is not

very common most plant and animal

species have an even number of

chromosomes due to sexual reproduction

where half of the chromosomes are

received from each parent and so humans

for example we have a total of 46

chromosomes in which we receive 23 from

Mom and 23 from Dad combined to produce

46 uh these sex cells these gametes each

have half so sperm and egg each have

those 23 and those cells are referred to

or called haploid cells because they

have half the number of chromosomes a

body cell uh like a skin cell or a

muscle cell would then have a diploid or

two sets of chromosomes and that would

be the total of

46 our nearest closest relative in terms

of chromosomes and similarities in DNA

are the chimpanzees and chimpanzees have

48 chromosomes the differences between

these two species is only about 2% of

the DNA it's not very much at all and

the difference in chromosome numbers uh

is actually most likely from the

combining of chromosomes uh in humans so

we have two less than what chimpanzees

do having more chromosomes does not

necessarily indicate a greater

complexity of that species um but plants

actually are are the types of species

that have the most number of chromosomes

uh because they can tolerate mutations

that result in duplicate or extra

chromosomes uh humans and other

mamillion species are not able to

tolerate that as much typically the the

developing zygote the fetus would not go

on to develop because of too many or or

unmatching chromosomes so we're not able

to tolerate that plants can tolerate

that more often um and this is this is

most important in that all members of

the species have the same number of

chromosomes it's really important that

members of the species have the same

number of chromosomes in order for that

species to be able to persist so as we

just discussed chromosomes appear during

cell division uh specifically during

prophase of mitosis and we can view

these by staining the cells and viewing

under a microscope uh having those cells

uh burst so that the the chromosomes are

not overlapping allows us to actually be

able to take a look at them and how we

do that uh after we've taken the chromos

romes and organize them is uh called a

kot type and this is a kot type here

staining of the DNA this is not natural

colors but staining of the of the

different chromosomes uh allows for

banding uh banding patterns to to be

present for each chromosome they also

vary in size and then the position of

the central mirror which holds the two

arms together the chromatids together uh

this position varies and so this allows

us to line up the similar chromosomes

one from Mom one from Dad uh and we can

take a look at the chromosomes for a

particular species and make comparisons

within the species or of different

species and this kot type is uh of

humans because we can see there's 1

through 22 the autosomal chromosomes and

then we also have uh sex chromosomes X

and Y in this case to better understand

the similarities and differences between

genome sequences of different species

and within species we need to look at

the unity unity and diversity a genome

is all of the DNA the genetic

information of an individual and that's

what makes up the genome

members of a species have the same DNA

with the same genes uh not necessarily

the same type of forms and in the same

sequence so to be a member of the

species you're going to have the same

number of chromosomes those chromosomes

will have the same genes uh the sequence

might be slightly changed and we'll talk

about that in a moment during the

process of meosis uh which is the

production of sex cells sperm and egg an

exchange of portions of chromosomes can

actually swap places and this process is

called crossing over it takes place

during prophase 1 of meosis we'll learn

about it a little bit later on in the

course and it actually leads to genetic

diversity it's essentially just a way to

mix up the combination of uh types of

genes and this is possible because

members of the species have the same

number of chromosomes and genes and so

that's a Unity that's unity in that the

species have the same number of

chromosomes we see diversity then

expressed in the actual genes and So

within a gene sequence a gene is a

section of DNA that's responsible for

coding for some proteins has the

instructions to be able to make some

proteins we'll talk about that process

later on uh there can be different types

A very simple example uh the ability to

uh bend your thumb uh it's called a

hitchhiker's thumb uh you can bend it

back uh I can't really B Bend mine back

um but that ability is controlled by a

single Gene and what makes that ability

present or not present is by the

difference of a single Nu cleotide an a

TG or

C having that or not having that that's

a different form or a different type uh

and so what we call a different form or

an alternate form of a gene uh is an Al

um and another example this is very much

simplifying it but if we look at the

trait of eye colors uh that's the

particular trait that we're looking at

there are different obviously there's

different types or colors of eye colors

and so blue uh brown green uh Hazel

those would all be different types of

eye colors and those would all be

different alals for the the trait of eye

color eye color is actually a polygenic

trait which means it has multiple genes

that control it so it's actually much

more complex but that's just a simple

explanation uh to demonstrate what is an

Al differences are usually only a small

number of bases so what makes each Al

different from one another is just a

small number of bases so that difference

could be as simple as instead of having

a cytosine in one particular section of

the gene it might be a thyine uh or an

Adine and and the simple changing or

exchanging of just one uh nucleotide can

make a difference uh and result in a

different form of that Gene a different

Al positions in the gene where more than

one base may be present are called

single nucleotide polymorphisms or Snips

uh for shorts thousands of human genome

sequences indicate that there's about a

100 million different Snips uh but most

of the three billion uh are the same

there's Unity amongst our species U and

per human there's about four to 5,000

Snips or one base in every 650,000 and

this is a cause of diversity within the

species while this one base in every

650,000 may not seem like a great

difference uh that would lead to a lot

of variation this is actually one of the

main uh factors that contributes to

variation within the human species not

surprisingly there is a wide diversity

in the Genome of eukariotic species and

all living species on the planet there's

a far greater amount of diversity or

variation between different species than

there is within members of the same

species and the in terms of the

variation in genome size uh how big the

genome is or how much DNA there is is

based on the number of base pairs or

individual nucleotides and so large it's

actually possible for large genomes to

have lots of nonfunctional DNA meaning

that they don't result or um are used

for the production of proteins and

within humans this this is actually

about half of our genome uh they're

called transposons or transposable

sequences of DNA and they don't have a

known function we're not entirely sure

what what their purpose is uh in the

past or oftentimes are referred to as

junk DNA there is some evidence that

maybe what we thought was junk DNA is

not necessarily true in a nutshell we

don't exactly know how DNA is used for

all mechanisms of life and and

controlling life and we're still

learning much um a as time goes on and

Technology improves within the variation

sequence uh and comparing the base

sequence of different species over time

two populations can acquire more and

more genome bases and they can become

more distinct in in species as they

diverge from a common ancestor uh and

although changes are not common uh

partic changes are not always common uh

particularly in genes that have a vital

function um and this is because it

provides a selective Advantage uh or

disadvantage um and it results in not

changing uh and having um having the

gene stay the same between very

different species and we see this

sometimes uh in in vital genes such as

the cytochrome C uh it's a mitochondrial

protein and it's used during respiration

to maintain ATP production our cells

need ATP which is a cellular energy to

be able to to carry out their functions

and so living organisms have to have

that ATP and the gene that helps to make

that happen is very very similar uh

between lots of different species and

and very different species and that's

what's being displayed in the chart here

we can compare humans to other species

and we see that that Gene and the amino

acids that are used to make the proteins

from that Gene are really really similar

different species have different numbers

and and types of genes and genes can be

added or removed um uh as species

diverge from a common ancestor and so we

we typically see them to progress slowly

as they adapt to different ways of life

in terms of their genome diversity the

ability to compare organisms and to

classify organisms for that matter has

really improved drastically just within

the last decade uh and this is all based

off of sequencing the entire Genome of

an organism looking at the entire base

sequence of an organism uh this was

first completed in the 90s with bacteria

and rki now it's possible with pretty

much all organisms as long as the DNA

can be extracted and collected for

humans it was first completed in about

2003 with about 3 million base pairs

sequenced uh the speed and the cost is

what's amazingly uh how quickly it's

changed and improved in

2001 uh it was about $100 million to

sequence a human's genome today it's

about or in 2020 uh it's about $1,000

and so that is a massive difference in

cost and opens up whole new applications

to be able to compare species and really

learn and investigate about the

evolutionary origins uh of different

species we can identify relationships

between species we can trace common

ancestors uh we can learn how to fight

infectious diseases one of the reasons

that uh the vaccines for coid were

produced so quickly was the ability to

extract sequence and examine the DNA uh

between the different variants according

to science there's about 30 million

people that have had their genome

sequenced and for humans particularly

this provides information and data about

human migration genetic diseases human

health uh and it opens opens up all

kinds of new doors for potential

personalized medicine in the future and

this is already starting to to be more

and more common uh having genome

sequenced to be able to provide more

directed medical applications and

techniques the uh the process of genome

sequencing is just going to open up and

make available all kinds of uh new

technologies and capabilities that we

have not had in the past as we mentioned

at the beginning of the video the

concept of biological species works for

many species but not for all and so now

let's discuss some of the the challenges

with that uh within sexual reproduction

uh it it ensures that there's a mixture

of genes and uh ensures that there's a

unity in terms of the number of

chromosomes within a species uh and this

is regardless uh if the species can

reproduce both sexually and asexually

Sometimes some species have the ability

to do both in asexual reproducing

species however offsprings are clones of

parents that are produced uh via mitosis

and and a good example of this would be

like blackberries and dandelion if

you've ever seen a Blackberry before it

has this little arm that shoots out and

once that hits dirt it it starts a new

plant you could cut the the arm between

the two and then you have two distinct

plants but they're clones of one another

they're identical and so um it it's

essentially making copies like in a copy

machine if the Clones don't interbreed

with other clones then they're

technically a separate species by that

biological species concept and so

blackberries have hundreds of clones uh

dandelion quickly have have hundreds of

clones also and so it's difficult to

apply the idea of the concept of species

to these particular types of organisms

another example would be the horizontal

Gene transfer that can occur between

bacteria um this would be where parent

to offspring uh is typically a vertical

transfer the parent uh provides genetic

information to The Offspring uh

horizontal Gene transfer would be from

one organism to another not necessarily

parent to offspring and this is common

among bacteria there is so much Gene

transfer that can occur the species

concept may not even apply to

procaryotes uh and it's far less

frequent in UK carots and so how this

works is the the bacteria uh one in our

picture transfers a gene uh signified by

Red to the other bacteria number two and

this is transformation and so there

sending exchanging genes between one

another uh not from parent to offspring

but just between two different

individuals and so this also makes it

really difficult to distinguish are

these different species or are they one

species and so again not everything

exactly fits this concept of biological

species members of the same species

typically have the same number of

chromosomes uh and and that number is

oftentimes different than other species

in or for sex production male and female

produce gamut cells that have the same

number of chromosomes and these gametes

are formed by the process of meosis in

diploid cells so like a body cell

there's two sets of chromosomes one from

Mom one from Dad and each chromosome

carries the same sequence of genes uh

they may have different uh forms of

those genes alal and those chromosomes

that carry the same genes we call

homologous chromosomes because they have

the same genes although those genes

might be slightly different types during

meosis those homologous chromosomes pair

up to ensure an equal separation to each

gamt cell and this helps

to ensure that each gamt cell has for

humans chromosomes 1 through 23 uh in

each one of those different cells and

then when those gamt cells sperme egg

fuse the chromosomes then match up and

it produces a zygote uh if the cells or

the gametes have different number of

chromosomes

uh this usually results in some unpaired

chromosomes and often times this would

result in non-viable cells so the zygote

doesn't even develop uh at best

typically the The Offspring would be

infertile and unfortunately this is how

we see some of our genetic disorders uh

occur in humans for example Down

syndrome is uh an individual that has an

extra of chromosome 21 so they have

three chromosomes uh for 21 rather than

the typical two do and there are other

diseases that are also uh possible

because of of extra or deleted

chromosomes usually though the the cells

will not be viable and

So within species chromosome num should

be the same uh for the for The Offspring

to be fertile and to be viable uh

between different species the chromosome

numbers are going to differ so for this

learning objective students are expected

to produce a dichotomous key for a local

plant animal uh if you're one of my

students in class will actually do this

together uh if you're not and you're

learning from somewhere else would

recommend that you spend some time

researching how to make a dichotomus key

there are some general steps outlined

here and then actually go about creating

one for yourself and having some

practice and familiar familiarity using

a dichotomus key because you may be

expected to do so on the exam as I

discussed just a minute ago the ability

to sequence CNA has really opened up all

kinds of new doors uh and applications

for Science and here is one of those

applications what we we call DNA

barcoding and this is a tool used to

identify unknown species from small

samples of DNA DNA samples can be taken

from water soil basically any part of

the abiotic environment uh and the

locations will contain DNA from

individuals interacting with that

environment and so we leave DNA around

on a regular basis as do other species

those species can be compared by looking

at different Gene regions to be able to

identify uh the organism groups or that

particular species and most common for

animals and some protos is used the use

of cytochrome C oxidase or the Cox one

Gene and it's found in mitochondrial DNA

that Gene can be used to identify an

unknown species um there's large amounts

of possibilities uh for the use of this

this technique forensic science um

identifying individuals uh suspects uh

food safety ecological assessments uh

species identification invas invasive

species detection it has a wide range of

different uses and applications uh and

so it's a really cool tool that

scientists and biologists have now to be

able to uh compare sequences and

identify unknown organisms