GCSE OCR GATEWAY BIOLOGY : What happens in cells (and what do cells need)? COMPLETE REVISION

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GCSE OCR Biology What happens in cells (and what do cell need )Complete Revision Summary

What happens in cells (and what do cells need)?

What happens in cells (and what do cells need)?
  • Rates of reaction

  • Protein synthesis – Higher

  • Enzymes

  • Factors affecting enzyme action

  • Practical – The effect of pH on the rate of reaction of amylase

  • Rates of reaction

DNA – Deoxyribonucleic acid

Deoxyribonucleic acid (DNA) is a large macromolecule made up of a large number of monomeric units of nucleotides. Each nucleotide is composed of nucleoside and a phosphate group

Chromosome – These are the structure that holds our genetic information

DNA – Double Helical Structure which contains genetic information

Gene – It is the segment of DNA that code for protein

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DNA : A POLYNUCLEOTIDE

HUMAN GENOME

  • Genome is the complete genetic materials of the organism.
  • International collaboration to sequence around three billion bases and more than 20,000 genes.

Importance of Human Genome Project

  1. a) Understanding of genetic Diseases and inherited disorders
  2. b) Better personalised medicines
  3. c) Understanding Evolution
  4. d) Indentifying new drugs target.

PROTEIN SYNTHESIS

  • The DNA copies the code and form mRNA by the process of transcription.
  • The mRNA leaves the nucleus and reaches the ribosome.
  • The ribosomes reads the bases in the sequence of three bases. The t-RNA brings the corresponding amino acid and forms polypeptide chain .
  • The polypeptide chain than forms proteins.

ENZYMES

  • They are biological catalyst that increases the rate of a biological reaction without being used up.
  • They increases the rate of the reaction by providing an alternative route that works by lowering the activation energy.
  • They are protein in nature so they are sensitive to heat and pH.

What happens in cells_ (1)-merged

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LOCK AND KEY MODEL

Enzymes are highly specific due to the active site. As the active site has a shape complimentary to the substrate. So the specific substrate molecule can fit into the active site of the enzyme.

FACTORS AFFECTING ENZYME ACTIVITY

SUBSTRATE CONCENTRATION

ENZYME CONCENTRATION

FACTORS AFFECTING ENZYME ACTIVITY

Temperature

Denaturation is the change in the shape of the enzyme with increase in temperature and pH beyond optimum which results in the change in shape of the active site As a result, substrate molecules can no longer fit into the active site decreasing the rate of the reaction.
  • Rate of reaction increases as particles gain kinetic energy and they collide more increasing
  • The optimum temperature. It is the point where the enzyme activity is the highest.

pH

  • Different enzymes has different pH optimum.
  • Stomach enzymes works in acidic conditions which are maintained by hydrochloric acid Intential enzymes works in alkaline pH maintained by bile

Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons

Image Source:

Wikipedia

Wikimedia

Commons

Flickr

Pixabay

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

Cell Structure And Transport