Unit 2 Module 1

HideShow resource information
  • Created by: HazelS
  • Created on: 05-05-15 09:20
Why is the genetic code referred to as a triplet code?
Every amino acid is coded for by 3 bases
1 of 36
There are 64 different DNA base combinations, how is this calculated?
4 x 4 x 4
2 of 36
Only 20 amino acids are used for protein syntehsis, explain what the other 44 base combinations are used for
Several triplets code for one amino acid. Start or stop. Mutations can have a neutral effect
3 of 36
What bases are common to DNA and RNA
A, G, C
4 of 36
What happens during translation?
Proteins are synthesised
5 of 36
Where does translation happen?
Ribosome
6 of 36
What type of nucleic acid holds the sequence of bases during tanslation?
mRNA
7 of 36
Why do stop codons cause the termination of polypeptide chain?
They do not code for an amino acid
8 of 36
What type of mutation is uuu to uuc
Point
9 of 36
Define gene
Short length of DNA which codes for a polypeptide
10 of 36
Explain what is meant by the term genetic code
Sequence of bases code for a polypeptide. Is a triplet code. Ech triplet code can code for an amino acid or stop codon. Is a degenerate code.
11 of 36
Why does a gene of 528 bases code for only 178 amino acids?
Triplet code. 525 base codes code for 175 amino acids. 3 bases for stop codon.
12 of 36
When analysed, why do two animals share 96% of amino acids in a polypeptide, but only 94% of the bases in the gene which codes for it?
Gene code is degenerate. More than one triplet code for the same amino acid. There are silent mutations. DNA can change more than proteins
13 of 36
Describe transcription
A gene unwinds and unzips. Activated RNA bases bind to complementary bases. One strand is copied. U-A, G-C, A-T. RNA polymerase involved. mRNA leaves through nuclear pore.
14 of 36
How is RNA polymerase and DNA polymerase different?
RNA polymerase makes RNA. RNA polymerase involved in transcription. RNA polymerase forms one strand. DNA polymerase involved in DNA replication. DNA polymerase forms two strands.
15 of 36
Describe how the information found in genes can be used to synthesise proteins?
DNA copied into mRNA. Transcription. Only one strand is copied. Free nucleotides. Complementary base pairing. Triplet code. Catalysed by RNA polymerase. Base sequence determines amino acid sequence. Translation occurs. mRNA moves to the ribosome.
16 of 36
Describe how the information found in genes can be used to synthesise proteins? cont.
Anticodon pair with codons. Correct amino acid attached to tRNA. Amino acidsjoin by peptide bond.
17 of 36
Outline the role of cyclic AMP
Activates proteins. By changing their 3D shape.
18 of 36
Outline the role of polypeptides
Structural proteins. Enzymes. Hormones. Receptor proteins. cAMP. Switching genes on/off. Homeodomain proteins.
19 of 36
What is meant by the term gene mutation?
Change to DNA
20 of 36
What is it called when a gene frequency changes without human interference
Natural selection
21 of 36
How can mutations have beneficial effects?
A new protein is produced. Which has a different shape and function. Which aids survival.
22 of 36
How can mutations have negative effects?
A new protein is produced. Which has a different shape. It does not function correctly. Reduces survival odds.
23 of 36
How can mutations have neutral effects?
Silent mutation. New triplet codes for the same amino acid. Protein produced has the same shape and function.
24 of 36
Which of the folloing will have the most effect, single base pair substitution, 21 base pair deletion, 13 base pair deletion.
13 base pair deletion has most effect. Frameshift has occured on 13 b.p's. Genetic code is triplet. Alters all amino acids after deletion. 21 b.p deletion causes 7 amino acids to be lost. Substitution mutation only changes one amino acid.
25 of 36
What is an allele?
An alternate version of a gene
26 of 36
How can an allele become common in a population
Natural selection. Survival advantage. Increases chance of survival. Allele passed down onto next generation. Allele frequency increases over time.
27 of 36
What is the difference between regulatory gene and structural gene?
Regulatory gene makes repressor protein. Structural gene makes proteins/enzymes. Regulatory gene controls the expression of structural gene.
28 of 36
Yogurt is made by bacteria aeobically respiring in milk, why is this suitable for lactose intolerant people?
Lactose has been respired by bacteria. To lactic acid. Yogurt is a good source of calcium.
29 of 36
Explain how the structural genes are turned on in the lac operon, in the presense of lactose
Lactose binds to repressor protein. Changes shape to repressor protein. Stops it binding to operaor. RNA polymerase bins to promoter. Genes Z and Y are transcribed. Beta-galactosidase and lactose permease produced.
30 of 36
Explain why the structural genes are turned off in the lac operon in the absense
Regulatory gene is transcribed and trnalsated into repressor protein. Repressor protein binds to promoter. Structural genes Z and Y are not transcribed.
31 of 36
Name the lac: i, p, o, z, y
i - regulatory gene. p - promoter region. o - operator region. z- structural gene for beta-galactosidase. y - structual gene for lactose permease
32 of 36
What is a homeobox gene
Homeotic gene. Contains homeobox sequence. Codes for a homeodomain on protein. Which binds to DNA. Switches genes on and off, Controls body plan.
33 of 36
Explain why there is very little change by mutation in homeobox genes
These genes are very important. Mutation would alter body plan. Many other genes would be affected. Mutation likely to be selected against.
34 of 36
Describe programmed cell death
Apoptosis. Cytoskeleton broken down. By enzymes. Cell membranes form blebs. Cell breaks into membrane bound fragments. Cell fragments broken down by phagocytosis.
35 of 36
What happens when a mutation means that apoptosis does not occur?
Mitosis of somatic cells occurs at a greater rate than apoptosis. Tumours form.
36 of 36

Other cards in this set

Card 2

Front

4 x 4 x 4

Back

There are 64 different DNA base combinations, how is this calculated?

Card 3

Front

Several triplets code for one amino acid. Start or stop. Mutations can have a neutral effect

Back

Preview of the back of card 3

Card 4

Front

A, G, C

Back

Preview of the back of card 4

Card 5

Front

Proteins are synthesised

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all DNA, genetics and evolution resources »