B2.1

Inside Living cells

Objectives

• The chemical reactions essential for life take place inside cells

• Respiring cells require a supply of glucose and oxygen, producing carbon dioxide as a waste product

• Genes are the template for protein synthesis inside cells

• The digestive, circulatory and respiratory systems provide cells with the basic materials they need to carry out their functions.

DNA

• In the nucleus of a cell are chromosomes, made up of genes, made up of DNA.

• DNA is like a set of instructions, called the genetic code

• DNA tells the cell to make specific proteins

• DNA a double helix • Click image!

Base pairs

• Adenine – Thymine• Guanine – Cytosine • To help you remember:• Alan Titchmarsh• George Clooney

Proteins

• Amino acids make up proteins• There are 20 amino acids• Their order determines the protein that is made• DNA unzips and copy of the coding strand of

DNA is made, it is called messenger RNA (mRNA) it make a mirror image BUT it uses Uracil (U) instead of Thymine.

• This is called transcription• After the mRNA has detached the DNA winds

back up, base pairing G-C to A-T

Each 3 bases make up a code that relates to a

different protein

There are 20 protein, many of them have a few codes, you do not

need to know the proteins!

THIS IS A LEVEL work so you do not

need to know it, but it makes it easier to

understand the triplet system

The Genetic code

Translation

• The mRNA leaves the nucleus and enters the cytoplasm

• The mRNA is taken to the ribosome• It is read by another type of RNA, Transfer RNA

tRNA which carries the amino acids • This is where triplets (3 bases, I amino acid)

attach to the mRNA to make a protein. tRNA molecules continue to bring amino acids until the chain is 10s or 100s long. This is a poly peptide.

• This now needs to be folded into a particular shape, to make a make it a working structure.

Click for video

Insulin is a globular protein.

A polypeptide once folded

and arranged correctly

becomes a functioning

protein

Fermentation

• Penicillin- mould called Penicillium • Yeast-bread, beer wine• Cheese, yoghurt- lactic acid bacteria• Quorn - Mycoprotien• Micro-organisms grow very fast they can

be kept under controlled conditions and grown in any country to make food.

Fermentation

• Micro-organisms are cultivated in a culture medium

• They use up the nutrient s and produce waste products

• Yeast given sugar, broken into CO2 and ethanol (alcohol)

• Fermenters are used to cultivate microbes to make many different products and different nutrients are added to produce different products.

Fermentation

• Bacteria have DNA like humans• So they can be used to make human

proteins, like insulin• Cut out the human insulin gene, stick it

into bacterial DNA, use a fermenter to produce lots of the Bactria which will produce a lot of insulin

Click for video

To avoid contamination

with other microbes the

fermenter but be sterile before anything is

added.

Aseptic measures must

be taken.

Usually cleaned with hot steam,

under high pressure.

Contamination can cause a low yield of product

Aerobic Respiration

glucose + oxygen carbon dioxide + water + energy

When you exercise your muscles need more energy, so the rate of respiration

needs to increase, you take in more oxygen and get rid of more carbon dioxide by

increased breathing rate.

Heart beats faster, to take more oxygen

away from your lungs to your cells a large

concentration gradient is maintained so that gas exchange occurs

more quickly.

The effects of exercise

More oxygen absorbed by lungs, More carbon dioxide is removed, More glucose and oxygen need to be delivered to your cells

This means that your breathing and heart rate will increase

Improving measurements• Taking your pulse by hand means you have to

take it over time, and stop exercise• Digital equipment is more reliable and you can

get instant results• Our core body temp is 37°C, it only changes by

a 1/10 of a degree during exercise, however our surface body temp will change

• Reliable means that you get the same results every time

• Precise means that the result are close to the real value

Anaerobic Respiration

Atkins diet

Go back to the

objectives and your

target sheet,

check on your

learning!