F215 Cellular Control Revision Notes

PDF file suitable for e-readers/e-books, also printable & viewed on a computer.

Overview of cellular control topic on the F215 OCR Biology syllabus.

Includes; DNA, transcription, translation, mutations, the lac operon, homeobox/hox genes & apoptosis.

Hope this helps!

HideShow resource information
  • Created by: Laurie
  • Created on: 26-05-13 13:44

Pages in this set

Page 1

Preview of page 1
OCR F215 Biology

Page 2

Preview of page 2
What is a Gene?

A gene is a unit of heredity
A gene is a sequence of nucleotide bases
found in DNA that codes for one or more
polypeptides.
Genes code for polypeptides which have
structural and metabolic roles e.g. keratin,
collagen, channel proteins, etc.

Page 3

Preview of page 3
The Genetic Code

The sequence of nucleotides on a gene
(length of DNA) provides a code with
instructions for making a polypeptide or
protein.
There are 4 different types of nucleotide
bases found in DNA: A,C,T,G. The genetic
code is a triplet code which means 3 bases
code for 1…

Page 4

Preview of page 4
Transcription

Gene unwinds & unzips. H-bonds break
between complimentary bases.
Activated RNA nucleotides bind to
exposed bases. U-A, G-C, A-T on template
strand. Catalysed by RNA polymerase.
The 2 extra phosphates are released-
energy released ­ adjacent bonding
between nucleotides.
mRNA is complementary to template
strand is a copy of…

Page 5

Preview of page 5
Transcription

Page 6

Preview of page 6
Translation

mRNA binds to a ribosome ­ first codon is
always AUG
tRNA with the complementary anticodon
forms H bonds with codon using ATP &
an enzyme.
A second tRNA with a different amino
acid binds to the next codon with its
complementary codon.
A peptide bond forms between the…

Page 7

Preview of page 7
Translation

The 1st tRNA leaves and picks up another
of its amino acids.
The polypeptide chain grows until a stop
codon is reached & the chain is now
complete.




cAMP (cyclic AMP) is a nucleotide
derivative which activates proteins by
changing their 3D shape so they are a
better fit…

Page 8

Preview of page 8
DNA Mutations

Are random changes in the genetic
material.
Substitution mutations ­ one base pair
replaces another is likely to change 1
amino acid. Changes to 2nd or 3rd base
pairs are less likely to cause a change in
amino acid production.
Insertion/Deletion mutations ­ one or
more base pairs…

Page 9

Preview of page 9
Chromosome
Mutations

Chromosome mutations are random
changes in the structure of a chromosome
such as translocations, deletions or
inversions of large sections.
May occur during DNA replication, or
may be caused by mutagens e.g. UV light,
x-rays & tar.

Page 10

Preview of page 10
Effects of
Mutations

Neutral effects ­ some mutations change
the base sequence, but if the mutation is in
the `jumk' DNA, it is a `silent mutation.'
This is also the case if a change in bases
has no advantage/disadvantage.
Harmful/beneficial effects ­ e.g. skin
colour; when the first humans lived…

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »