GCSE Biology Revision "Sizes of Cells"

Summary

In this educational video from Freez lessons, viewers are introduced to the concept of measuring cell sizes using scientific units. The video explains the use of metric prefixes such as centi, milli, micro, and nano to describe sizes in biology, which are often smaller than everyday objects. It covers the conversion from meters to centimeters, millimeters, micrometers, and nanometers, highlighting their applications in describing the dimensions of cells and cellular components. The video emphasizes the practicality of these units, especially in the context of cell biology, and encourages practice with the provided workbook.

Takeaways

• 🔬 The video discusses the sizes of cells and introduces scientific prefixes to describe them.
• 🐕 A German shepherd's average length is used as a reference point, being about 1 meter.
• 📏 The prefix 'centi' means 100th, and 1 centimeter (cm) is 1/100th of a meter or 1 × 10^-2 meters.
• 🖊️ The width of a little finger is approximately 1 cm, and the tip of a ballpoint pen is about 1 mm.
• 🔢 The prefix 'milli' means 1,000th, and 1 millimeter (mm) is 1/1,000th of a meter or 1 × 10^-3 meters.
• 🐕‍🦺 In biological terms, 1 millimeter is quite large, as a dog is 1,000 mm long, which is 1 meter.
• 🔬 Scientists use even smaller units like micrometers for cell sizes, with the prefix 'micro' meaning 1 millionth.
• 🌌 A micrometer (μm) is 1 × 10^-6 meters, and typical human cells range from 10 to 20 micrometers in size.
• 🔍 The prefix 'nano' means one billionth, and 1 nanometer (nm) is 1 × 10^-9 meters, used to measure very small biological structures like proteins.
• 📚 The video encourages practice with the provided vision workbook for questions on cell sizes.

Q & A

What is the main focus of the video from Freez lessons?

The main focus of the video is to teach viewers how to describe the size of cells and how to use the prefixes centi, milli, micro, and nano.

Why might the material in the video seem tricky to some viewers?

The material might seem tricky because it involves understanding the size of cells and the use of scientific prefixes, which could require multiple viewings to grasp.

What is the difference between eukaryotic and prokaryotic cells in terms of size as mentioned in the video?

Prokaryotic cells are much smaller than eukaryotic cells.

What is the average length of a German shepherd mentioned in the video, and how is it measured?

The average length of a German shepherd is around 1 meter (M).

What does the prefix 'centi' mean and what is its symbol in standard form?

The prefix 'centi' means 100th, and in standard form, it is represented as 1 * 10^-2 m.

How is the width of a little finger related to centimeters?

The width of a little finger is around 1 centimeter (cm).

What does the prefix 'milli' mean and what is its symbol in standard form?

The prefix 'milli' means 1,000th, and in standard form, it is represented as 1 * 10^-3 m.

What is the approximate size of a typical human cell in micrometers?

A typical human cell is around 10 to 20 micrometers in size.

What does the prefix 'nano' mean and what is its symbol in standard form?

The prefix 'nano' means one billionth, and in standard form, it is represented as 1 * 10^-9 m.

Why are nanometers a useful unit for biologists?

Nanometers are a useful unit for biologists because they allow for the measurement of very small objects such as proteins and other cellular components.

What is the approximate diameter of a molecule of hemoglobin in nanometers?

A molecule of hemoglobin is around 5 nanometers in diameter.

Outlines

00:00

🔬 Introduction to Cell Sizes and Measurement Prefixes

This paragraph introduces the topic of cell sizes and the importance of understanding various measurement prefixes. The video aims to teach viewers how to describe the size of cells using the prefixes 'centi', 'milli', 'micro', and 'nano'. It highlights the difference in size between prokaryotic and eukaryotic cells, with the former being significantly smaller. The script explains that scientific measurements are based on the meter but often require smaller units for biological objects. It provides examples of converting meters to centimeters and millimeters, and then introduces the micrometer and nanometer as units for measuring smaller biological entities like cells and their components. The paragraph concludes with a mention of the usefulness of these units in biology and hints at future topics, such as the size of ribosomes.

Keywords

💡Eukaryotic cells

Eukaryotic cells are a type of cell that contains a nucleus and other membrane-bound organelles. They are more complex than prokaryotic cells and are found in organisms like animals and plants. In the video, the distinction between eukaryotic and prokaryotic cells is highlighted as a key difference, with eukaryotic cells being larger in size.

💡Prokaryotic cells

Prokaryotic cells are simpler cells without a nucleus or membrane-bound organelles. They are typically found in bacteria and are smaller in size compared to eukaryotic cells. The video script emphasizes that one of the key differences between prokaryotic and eukaryotic cells is the size, with prokaryotic cells being much smaller.

💡Meter

The meter is the base unit of length in the International System of Units (SI). It is used as a reference for all measurements of length in science. The script explains that all sizes in science are based on the meter, but biological objects are often much smaller, necessitating the use of smaller units like centimeters and millimeters.

💡Centimeter

A centimeter is a unit of length equal to one-hundredth of a meter. It is denoted by the prefix 'centi-', meaning 100th. In the video, centimeters are introduced as a way to describe the size of larger biological objects, such as the width of a little finger or the length of a dog.

💡Millimeter

A millimeter is a unit of length equal to one-thousandth of a meter. It is denoted by the prefix 'milli-', meaning 1,000th. The video uses millimeters to describe even smaller biological objects, such as the tip of a ballpoint pen.

💡Micrometer

A micrometer is a unit of length equal to one-millionth of a meter. It is denoted by the prefix 'micro-', meaning 1,000,000th. The video explains that a typical human cell is around 10 to 20 micrometers in size, making the micrometer a very useful unit for biologists when examining cells.

💡Nanometer

A nanometer is a unit of length equal to one-billionth of a meter. It is denoted by the prefix 'nano-', meaning 1,000,000,000th. The script mentions that nanometers are used to measure very small objects within cells, such as proteins, indicating the extremely small scale at which cellular components operate.

💡Standard Form

Standard Form, also known as scientific notation, is a way of expressing numbers that are too large or too small to be conveniently written in decimal form. It is used in the video to express measurements in terms of powers of ten, such as 1 cm being written as 1 x 10^-2 m, which is a common practice in scientific communication.

💡Prefixes

Prefixes are used in the metric system to denote specific powers of ten. In the video, prefixes like 'centi-', 'milli-', 'micro-', and 'nano-' are introduced to describe different orders of magnitude in length measurements. These prefixes are essential for understanding the size scales discussed in the context of cellular biology.

💡Hemoglobin

Hemoglobin is a protein found in red blood cells that is responsible for carrying oxygen. The video uses hemoglobin as an example of a molecule measured in nanometers, highlighting the application of nanometer-scale measurements in understanding the structure and function of cellular components.

💡Ribosomes

Ribosomes are cellular structures that play a central role in protein synthesis. The script mentions that cells contain small parts like ribosomes, which will be discussed in later videos. This suggests that understanding the size of cellular components, down to the nanometer scale, is crucial for studying cell biology.

Highlights

Introduction to describing the size of cells using scientific prefixes.

Explanation of the difficulty in grasping the size of cells due to their small size.

Comparison of the size differences between eukaryotic and prokaryotic cells.

Definition and use of the metric system's base unit, the meter, in biological contexts.

Introduction to the prefix 'centi' meaning 100th, and its relation to the centimeter.

Conversion of centimeters to meters using standard form notation.

Description of the size of a German shepherd dog to illustrate the concept of a meter.

Introduction to the prefix 'milli' meaning 1,000th, and its relation to the millimeter.

Conversion of millimeters to meters using standard form notation.

Example of the size of a ballpoint pen tip to illustrate the concept of a millimeter.

Introduction to the prefix 'micro' meaning one millionth, and its relation to the micrometer.

Conversion of micrometers to meters using standard form notation.

Description of the typical size of a human cell using micrometers.

Introduction to the prefix 'nano' meaning one billionth, and its relation to the nanometer.

Conversion of nanometers to meters using standard form notation.

Explanation of the importance of nanometers in measuring proteins and cells.

Example of the size of a hemoglobin molecule in nanometers.

Encouragement to practice describing cell sizes using the learned prefixes.

Transcripts

[Music]

hi and welcome back to Freez lessons.

co.uk by the end of this video you

should be able to describe the size of

cells you should then be able to use the

prefixes CTI Millie micro and

Nano now I should point out that this

material may seem quite tricky you might

need to watch this video a couple of

times to get the

ideas in the last video we started

looking at cells we looked at the

similarities and differences between

eukariotic cells such as animal and

plant cells and procaryotic cells such

as

bacteria one of the key differences is

that procaryotic cells are much smaller

than eukariotic cells in this video

we're going to look at the sizes of

cells so let's get started all sizes in

science are based on the meter but the

problem is that objects in biology are

often much smaller than that let's look

at some

examples I'm sure sh you here a German

shepherd and the average length of a dog

like this is around 1 M now if we divide

1 M into 100 equal parts then we've got

1

cm the word CTI means 100th so 1 cenm is

100 of a meter now scientists often use

standard form and you could be expected

to use that in your exams 1 cm is 1 * 10

^ of - 2

m just to give you an idea of the size

of that the width of your little finger

is around 1

cm now again in biology 1 cm is large if

we divide 1 cm into 10 equal parts then

we've got 1 mm so 1 cm is 10

mm again just to give you an idea of

that the tip of a ballpoint pen is

around 1

mm now the word Millie means 1,000th so

1 mm means 1,000th of a meter and again

using Standard Form 1 mm is 1 * 10^ of -

3

m going back to the dog we can see that

this is 1,000 mm long in other words 1

M now again in biology 1 millim is

pretty big so scientists work with even

smaller

sizes if we take a meter and divide this

into 1 million equal parts then we've

got a

micrometer the word micro means 1

millionth so one micrometer is 1

millionth of a meter a micrometer has

this symbol and I'd recommend that you

learn

that in standard form 1 micrometer is 1

* 10 the^ of - 6

M now a typical human cell such as this

one is around 10 to 20 micrometers in

size that means that biologists find a

micrometer a very useful unit especially

when looking at

cells now cells contain small Parts such

as ribosomes and we're going to look at

those in a later video this means that

we need an even smaller unit to talk

about the sizes of objects inside

cells so the final unit we're going to

look at is called the

nanometer the word Nano means one

billionth so 1 nanometer is 1 billionth

of a meter in standard form a nanometer

is 1 * 10 ^ of - 9 M now I should point

out that a nanometer is a very small

size Pro proteins and cells are measured

using nanometers this shows the protein

hemoglobin which is found in red blood

cells a molecule of hemoglobin is around

5 nanometers in

diameter remember you'll find plenty of

questions on the size of cells in my

vision workbook which you can get by

clicking on the link above okay so

hopefully now you should be able to

describe the size of cells you should

then be able to use the prefixes CTI

Millie micro and

Nano

[Music]