b2.1 inside living cells. objectives the chemical reactions essential for life take place inside...
TRANSCRIPT
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
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