Chemicals of Life - Nucleic Acids - Post 16 Biology (A Level, Pre-U, IB, AP Bio)

Summary

This script introduces nucleic acids, comprising DNA, RNA, and ATP. DNA is a double-stranded molecule with a double helix structure, made of nucleotides containing a phosphate group, deoxyribose sugar, and nitrogenous bases (cytosine, thymine, adenine, guanine). The strands run antiparallel, with bases pairing complementarily (A-T, C-G). RNA is single-stranded, with ribose sugar and uracil instead of thymine. ATP, a nucleotide with adenine, ribose, and three phosphate groups, serves as the cell's energy currency, releasing energy upon bond breakage.

Takeaways

• 🧬 Nucleic acids are composed of nucleotides, which include a phosphate group, a pentose sugar, and a nitrogenous base.
• 🌟 DNA (Deoxyribonucleic acid) is a well-known nucleic acid made up of nucleotides with four different bases: adenine, thymine, cytosine, and guanine.
• 🔍 The DNA structure is a double helix, resembling a twisted ladder, with each strand being a polymer of nucleotides.
• 🔗 DNA nucleotides are linked by phosphodiester bonds, formed through condensation reactions that remove water.
• 🌐 DNA strands are antiparallel, with one strand running in the opposite direction to the other, facilitating base pairing.
• 🤝 Complementary base pairing in DNA involves adenine pairing with thymine and cytosine pairing with guanine.
• 🧵 RNA (Ribonucleic acid) is structurally similar to DNA but has three key differences: it's single-stranded, uses ribose instead of deoxyribose, and contains uracil instead of thymine.
• 🔋 ATP (Adenosine triphosphate) is a nucleotide that contains three phosphate groups and is crucial for cellular energy transfer.
• ⚡ Breaking the bond between the last two phosphates in ATP releases energy, which cells use for metabolic processes.
• 🔄 ATP is often referred to as the 'energy currency' of the cell, highlighting its role in providing energy for various cellular functions.

Q & A

What are nucleic acids composed of?

Nucleic acids are composed of nucleotides, which consist of a phosphate group, a sugar (pentose), and a nitrogenous base.

What are the three types of nucleic acids mentioned in the script?

The three types of nucleic acids mentioned are deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and adenosine triphosphate (ATP).

What is the structure of DNA?

DNA has a double helix structure, which is like a twisted ladder, with each ladder rung being a pair of nucleotides.

What are the four different nucleotides that make up DNA?

The four different nucleotides that make up DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).

What is the sugar component of DNA nucleotides?

The sugar component of DNA nucleotides is deoxyribose.

How are nucleotides linked together in DNA?

Nucleotides are linked together in DNA by phosphodiester bonds, which are formed through condensation reactions that remove water.

What is the significance of the antiparallel arrangement of DNA strands?

The antiparallel arrangement of DNA strands means that one strand runs in one direction and the other in the opposite direction, allowing for complementary base pairing.

What is complementary base pairing in DNA?

Complementary base pairing in DNA is the specific pairing of nucleotide bases where adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

How does RNA differ from DNA?

RNA differs from DNA in that it is single-stranded, it contains the sugar ribose instead of deoxyribose, and it contains uracil instead of thymine.

What is ATP and why is it important for cells?

ATP, or adenosine triphosphate, is a nucleotide with adenine as its base, ribose as its sugar, and three phosphate groups. It is crucial for cells because breaking the bond between the last two phosphates releases energy that cells use for metabolic processes.

How many hydrogen bonds are there between adenine and thymine in DNA?

There are two hydrogen bonds between adenine and thymine in DNA.

How many hydrogen bonds are there between cytosine and guanine in DNA?

There are three hydrogen bonds between cytosine and guanine in DNA.

Outlines

00:00

🧬 Nucleic Acids: Structure and Components

This paragraph introduces nucleic acids, which are composed of nucleotides consisting of a phosphate group, a pentose sugar, and a nitrogenous base. The paragraph focuses on three key nucleic acid molecules: DNA, RNA, and ATP. DNA is highlighted as a double-stranded molecule with a double helix structure, where each strand is composed of nucleotides. The nucleotides in DNA are of four types, distinguished by their bases: adenine and guanine (purines), and cytosine and thymine (pyrimidines). The strands are antiparallel, with bases pairing through hydrogen bonds in a complementary manner (A with T and C with G). The paragraph also briefly mentions the structure of RNA, which differs from DNA in being single-stranded, having ribose as its sugar, and containing uracil instead of thymine. Lastly, ATP is introduced as a nucleotide with three phosphate groups, important for energy transfer within cells.

05:02

🔋 ATP: The Energy Currency of the Cell

The second paragraph delves into ATP, or adenosine triphosphate, which is a nucleotide with three phosphate groups. It explains that the hydrolysis of the bond between the last two phosphates releases energy, making ATP a crucial molecule for cellular energy needs. ATP is likened to the 'batteries' of the cell, powering various metabolic processes. The paragraph emphasizes the importance of ATP in cellular energy management.

Keywords

💡Nucleic Acids

Nucleic acids are the molecules that carry genetic information in living organisms. They are composed of nucleotides and include DNA and RNA. In the script, nucleic acids are introduced as the final group of biological molecules to be learned about, highlighting their importance in the study of biology.

💡Nucleotides

Nucleotides are the building blocks of nucleic acids. Each nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogenous base. The script explains that nucleotides are the fundamental units that make up DNA, RNA, and ATP, and their structure is crucial for understanding how these molecules function.

💡DNA (Deoxyribonucleic Acid)

DNA is a nucleic acid that contains the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. The script describes DNA's structure as a double helix, composed of two strands with nucleotides arranged in a specific sequence that encodes genetic information.

💡RNA (Ribonucleic Acid)

RNA is another type of nucleic acid that is involved in using the information encoded in DNA to produce proteins. The script points out that RNA is structurally different from DNA, being a single-stranded molecule with a different sugar (ribose) and a different base (uracil instead of thymine).

💡ATP (Adenosine Triphosphate)

ATP is the primary molecule for storing and transferring energy within cells. The script explains that ATP is a nucleotide with three phosphate groups attached to the sugar ribose. It's highlighted as a crucial molecule because when the bond between the last two phosphates is broken, it releases energy needed for cellular processes.

💡Pentose

Pentose refers to a type of sugar with five carbon atoms. In the context of the script, the sugar component of nucleotides is a pentose, specifically deoxyribose in DNA and ribose in RNA and ATP. Pentose sugars are essential for the structure and function of nucleic acids.

💡Base Pairing

Base pairing is the specific pairing of two nucleotide bases, guided by the principle of complementary base pairing. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). The script uses this concept to explain how the two strands of DNA are held together by hydrogen bonds between these pairs.

💡Phosphodiester Bond

A phosphodiester bond is a type of chemical bond that links nucleotides together in a nucleic acid strand. The script describes how these bonds are formed through condensation reactions, which involve the removal of water molecules, to create the backbone of DNA and RNA molecules.

💡Antiparallel

Antiparallel refers to the orientation of the two strands of DNA. The script mentions that the strands run in opposite directions, with one strand having a 5' to 3' orientation and the other a 3' to 5' orientation, which is essential for DNA replication and transcription.

💡Polynucleotides

Polynucleotides are long chains of nucleotides linked together by phosphodiester bonds. The script uses the term to describe the structure of a single strand of DNA or RNA, emphasizing that these chains are composed of repeating units of nucleotides.

💡Complementary

Complementary in the script refers to the concept of complementary base pairing in DNA. The bases adenine (A) and thymine (T), and cytosine (C) and guanine (G) are complementary because they fit together perfectly through hydrogen bonding. This is crucial for DNA replication and ensuring genetic information is accurately copied.

Highlights

Nucleic acids are composed of nucleotides, which consist of a phosphate group, a pentose sugar, and a nitrogenous base.

DNA, RNA, and ATP are the three nucleic acid molecules that will be covered in the course.

DNA has a double helix structure, resembling a twisted ladder made of nucleotides.

Nucleotides in DNA are of four types, with cytosine and thymine being purines, and adenine and guanine being pyrimidines.

DNA is composed of two antiparallel strands, with the sugar deoxyribose indicating the 'D' in DNA.

The bases in DNA pair up through complementary base pairing, with A always pairing with T and C with G.

The direction of DNA strands is indicated by the terms five prime and three prime ends.

RNA is similar to DNA but differs in being single-stranded, having ribose instead of deoxyribose, and containing uracil instead of thymine.

ATP, or adenosine triphosphate, is a nucleotide with three phosphate groups and is crucial for cellular energy transfer.

The breaking of the bond between the last two phosphates in ATP releases energy for cellular metabolic processes.

Nucleotides are linked together by condensation reactions, forming phosphodiester bonds.

DNA's double helix is stabilized by hydrogen bonds between the base pairs.

The structure of RNA will be revisited in the course to explore its functions and role in the cell.

ATP is often referred to as the 'battery' of the cell due to its role in energy storage and release.

The significance of the double helix structure in DNA for genetic information storage and replication.

The importance of complementary base pairing in DNA for accurate replication and transcription.

The role of the five prime and three prime ends in DNA synthesis and processing.

The structural differences between DNA and RNA and their implications for their functions.

Transcripts

now the final group of biological

molecules are going to learn about in

this section are nucleic acids now

nucleic acids are made up of nucleotides

a nucleotide has three parts to it a

phosphate group a sugar which will be a

pentose five carbon sugar and a base

nitrogenous base which contains nitrogen

now there are three molecules that are

made up of these nucleotides that you're

going to be coming across in the course

these include deoxyribonucleic acid DNA

ribonucleic acid RNA and adenosine

triphosphate or ATP we'll look at DNA

first as it's probably the one you've

heard about most so DNA structure may

look very complicated but actually it's

quite simple if you break it down into

its component parts it has this special

shape this double helix as it's called

which is basically a ladder that's been

twisted up and each ladder is a strand

of DNA it's a polymer made up of many

repeating units called nucleotides the

nucleotides come in four different

versions and when you join nucleotides

together in a long chain to make a

strand we call them poly nucleotides or

this is an example of a nucleic acid as

I've already mentioned nucleotides have

three parts so the nucleotides that make

up DNA contain the phosphate group like

we said they contain sugar and in this

case the sugar is deoxyribose which is

where DNA the D part of DNA comes from

deoxyribonucleic acid and the base as I

said there are four different

nucleotides that make up DNA and those

very base because of these bases the

four bases that you can have our

cytosine thymine which are both examples

of purine bases and then there are two

other ones adenine and guanine which for

example of pyrimidine bases

each nucleotide is linked to the next

nucleotide by a condensation reaction

just like condensation reactions that

we've seen before this is a reaction to

make a bond covalent bond which will

remove water the bond formed in this

case is called a phosphodiester bond so

when you join lots of nucleotides

together with lots of condensation

reactions and make these phosphodiester

bonds we end up with a poly nucleotide

or a nucleic acid and that makes one

strand of the DNA but to make DNA it's a

double-stranded molecule we need to

another strand we need an opposing

strand and the Strand is actually

arranged in the opposite direction it's

what we call anti parallel so one goes

in one direction the other strand goes

in the opposite direction the bases

always pair up between these two strands

in the same way a purine base will

always pair with a pyrimidine base this

means that a always pairs with T and C

always pairs with G it's what we call

complementary base pairing in order to

explain the direction of the Strand we

use the terms five prime and three prime

the end with the spare phosphate

sticking out is the five prime end the

two strands are joined together by

hydrogen bonds between the base pairs

there are two hydrogen bonds between a

and T and there are three hydrogen bonds

between C and G so the second nucleic

acid we're gonna look at is called RNA

and it's actually very similar to DNA

apart from three major differences RNA

is a single stranded molecule it's not

double stranded like DNA RNA it has a

different sugar in its nucleotides in

DNA is deoxyribose but in RNA it's

ribose RNA does not contain the base

thymine it contains uracil instead so

while in DNA you had adenine thymine

guanine and cytosine in RNA you have

adenine guanine and cytosine but then

you have uracil instead of thymine we're

coming back in the course many times to

look at RNA and it's

functions and how it's used by cells but

for now we're just going to look at the

structure of it the final nucleic acids

we're gonna learn about is ATP again

we're going to learn about ATP a lot

more when you look at respiration and

the process of respiration and how

energy is used in the cell ATP stands

for adenosine triphosphate and it is a

nucleotide which contains the base

adenine it's got the sugar ribose and

instead of having one phosphate group

actually three phosphate groups attached

now this is important because if you

break the covalent bond between the last

two phosphates it releases a little bit

of energy and this is why ATP are like

the batteries for a cell the cell will

use ATP and break that bond to release

the energy to for all its metabolic

processes