Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 6 > Cellular control > Flashcards

Cellular control Flashcards

1
Q

What is a mutation

A

A random change to the genetic material - (DNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When do gene mutations occur

A

Spontaneously during DNA replication before mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can cause gene mutations

A

Certain chemicals i.e. tar in tobacco smoke, ionising radiation (UV light, X-rays, gamma rays)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the difference between mutations in mitosis compared to mutations in meiosis

A

Mitosis (somatic mutation) not passed onto offspring
Meiosis - may be inherited by offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two main classes of DNA mutation

A

Point mutation: one base pair replaces (is substituted) for another
Indel mutations: Both insertions/deletions cause a frameshift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the three types of point mutations

A

-Silent
-Missense
-Nonsense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What reduces the chance of a mutations

A

The genetic code is degenerate - amino acids have more than one base triplet code

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Silent mutations

A

A change in the base triplet, where the triplet still codes for the same amino acid
-The primary/secondary/tertiary structure remains unaltered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Missense mutations

A

A change to the base triplet sequence that leads to a change in the amino acid sequence of a protein
-Alters the primary structure thus the tertiary structure is altered and the protein will no longer be able to perform its function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Example of a missense mutation

A

Sickle cell anaemia - Valine on the sixth base triplet instead of glutamic acid is inserted
-Results in deoxygenated haemoglobin crystallising within erythrocytes, causing them to become sickle-shaped, which blocks capillaries and deprives tissues of O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When may missense mutations not matter

A

-When the changed amino acid has a similar R group/ codon to the original
- If the changed amino acid does not make up part of the proteins active site so the protein can still perform its function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Nonsense mutations

A

May alter a base triplet so it becomes a termination (stop) triplet
-Results in a truncated protein that will not function
-Degraded within the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What disease is the result of nonsense mutations

A

Duchenne muscular dystrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do indel mutations involve

A
  • Insertion/deletion of a base that causes a frameshift
  • Can cause expanding triplet nucleotide repeats
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Insertions/deletions

A
  • If nucleotide base pairs (not in multiples of threes) are inserted in the gene/ deleted from the gene as the code is non-overlapping and read in codons all the subsequent base triplets will be altered
    -The primary and subsequently the tertiary structure will be altered and the protein will not be able to perform its function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens if the protein is very abnormal

A

It is rapidly degraded within the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What diseases can occur due to insertions/ deletions

A

thalassaemia - a haemoglobin disorder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is the insertion/deletion of a triplet of base pairs not an indel mutation

A

Results only in the gain/loss of an amino acid and not in a frame shift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Expanding triplet repeats

A

Amino acid triplet repeats ( - CAG,CAG,CAG-) increase in meiosis through each generation
- Five repeats could be inserted in one division and then in the next another three are added etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What disease occurs due to expanding triplet repeats

A

Huntington’s disease - when repeats go above a critical number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why are all mutations not harmful

A

Some are beneficial and have helped drive evolution through natural selection.
-Different alleles of the same gene are provided via mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What mutations in humans are neither beneficial or harmful

A
  • Inability to smell certain flowers i.e. freesias and honeysuckle
    -Different shaped earlobes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Name the different parts of the lac operon and their function

(The control region)

A

Promoter region - where RNA polymerase binds to begin transcription
lac O (operator region) - Binds to the repressor gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Name the different parts of the lac operon and their function

(Structural genes)

A

lac z - transcribes mRNA that will translate B galactosidase
lac y - transcribes mRNA that will translate lactose permease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

B galactosidase function

A

Hydrolyses lactose to glucose and galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Lactose permease function

A

Allows lactose to enter the bacterial cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Regulator gene I function

A

Not part of the lac operon

When switched on codes for the repressor gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens on the lac operon when glucose is present
(E-coli)

A

1) Regulator gene I is expressed and a repressor protein is produced
2) Repressor protein binds to the operator (lac O) and prevents RNA from binding to the promoter region
3) Repressor protein prevents lax Z and lac Y from being expressed so enzymes for lactose metabolism are not made (genes are switched off)
4) This prevents waste of amino acids and energy as e-coli can respire the glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happens on the lac operon when lactose is present (E-coli)

A

1) When lactose is added to the culture medium lactose binds to the repressor protein
2) This alters the repressor proteins shape and it can no longer bind to the operator region
3) RNA polymerase can bind to the promoter and begin to transcribe the structural genes into mRNA that will translate the two enzymes
4)E-coli can increase the uptake of lactose as it can induce enzymes to break itself down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the advantage of the lac operon system in e-coli only inducing the enzymes when lactose is present

A

It does not waste amino acids and energy to induce the production of enzymes to break down lactose as it can respire glucose when it is present and they are not needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is a transcription factor

A

A protein/ short non-coding piece of RNA

32
Q

What does the transcription factor do

A

An extra step in eukaryotes in transcription
-Once its bound to the promoter it makes it either easier/harder for RNA polymerase to bind to the promoter
-Transcription factor /s either activates or suppresses transcription of the structural gene

33
Q

Transcription in eukaryotes when transcription factor activates transcription of the structural gene

A

1) Promoter and structural gene
2) Transcription factor binding to the promoter
3) RNA polymerase also attaches to the promoter and transcription of the structural gene can begin

34
Q

Transcription in eukaryotes when transcription factor suppresses transcription of the structural gene

A

1) Promoter and structural gene
2) Transcription factor binding to the promoter
3) RNA polymerase cannot attach to the promoter as the transcription factor suppresses the transcription of the structural gene as it inhibits the RNA polymerase from binding

35
Q

What does post-transcriptional gene regulation involve

A

Introns and exons

36
Q

Introns

A

Noncoding region of DNA; sequence of nucleotides within a gene that does not remain in the mRNA transcribed from that gene

37
Q

Exons

A

The coding, or expressed region of DNA; a nucleotide sequence within a gene that remain in the final mRNA transcribed from that gene

38
Q

Post-transcriptional gene regulation - what happens?

A

1) Both introns and exons are transcribed from DNA, resulting in primary mRNA
2) The introns are then removed and the exons are joined together
3) Resulting in mRNA (exons) and introns are used as transcription factors or to encode proteins

39
Q

What is mRNA called with both introns and exons

A

Primary mRNA

40
Q

What enzymes are involved in the editing and splicing process

A

Endonuclease

41
Q

What can DNA do depending on how it is spliced

A

Encode for more than one protein

42
Q

What does post-translational level of gene regulation involve

A

Involves the activation of proteins

43
Q

How are enzymes activated

A

By being phosphorylated

44
Q

How does cAMP activate enzymes and also may help stimulate transcription
1-4 (to the formation of cAMP)

A

1) A signalling molecules such as glucagon, bind to receptor on plasma membrane of the target cell
2) Activates G protein
3) G protein activates adenyl cyclase
4) Activated adenyl cyclase enzymes catalyse the formation of many molecules of cAMP from ATP

45
Q

How does cAMP activate enzymes and also may help stimulate transcription (5-6)

A

5) cAMP activates PKA (protein kinase A)
6) Activated PKA catalyses the phosphorylation of various proteins, hydrolysing ATP in the process. This phosphorylation activates many enzymes in the cytoplasm i.e. those that convert glycogen to glucose

46
Q

How does cAMP activate enzymes and also may help stimulate transcription (7-8)

What can the activated protein PKA also do

A

7) PKA may also phosphorylate another protein (CREB)
8) This then enters the nucleus and acts as a transcription factor to regulate transcription

47
Q

Apoptosis

A

Programmed cell death

48
Q

Process of apoptosis - what happens?
1-6

A

1) Enzymes break down cell cytoplasm
2) The cytoplasm becomes dense with tightly packed organelles
3) The plasma membrane changes and small protrusions called blebs form
4) Chromatin condenses, the nuclear envelope breaks and DN breaks into fragments
5) The cell breaks into vesicles that are ingested by phagocytic cells; so that cell debris does not damage any other cells/tissues
6) The whole process happens quickly

49
Q

What helps to control apoptosis

A

Cell signalling molecules - respond to both external and internal cell stimuli i.e. stress

Plays a crucial role in making sure the right amount of apoptosis occurs

50
Q

Examples of cell signalling molecules that help to control apoptosis

A

Cytokines, hormones, growth factors, nitric oxide

51
Q

Nitric oxide - what does it do?

A

Can induce apoptosis by making the inner mitochondrial membrane more permeable to hydrogen ions and removing the proton gradient
-The proteins are then released into the cytoplasm and bind to apoptosis inhibitor proteins, which allows apoptosis to occur

52
Q

Benefits of apoptosis

A

-Can prevent the extensive proliferation of cells, without needing the release of hydrolytic enzymes, which can damage cell tissue
-During limb development, apoptosis causes the digits to separate from each other
-Removes ineffective/harmful T lymphocytes during the development of the immune system

53
Q

How much should apoptosis occur and what happens if there is too much/too little of it

A

The rate of cells dying = The rate of cells produced by mitosis
- Not enough apoptosis leads to the formation of tumours
-Too much apoptosis leads to cell loss and degeneration

Cell signalling plays a crucial role in maintaining the right balance

54
Q

How does apoptosis differ from necrosis

A

Necrosis is caused by trauma i.e. pathogens
- Releases hydrolytic enzymes = can damage other cells

55
Q

What are homeotic genes

A

The genes in DNA that regulate morphogenesis

56
Q

What is morphogenesis

A

The process that causes an organism to form its shape

57
Q

What is a subset of homeotic genes called

A

Homeobox genes = codes for the protein

58
Q

What is the homeobox sequences

A

Part of the homeobox gene is an 180 base pair length of DNA

59
Q

What does a homeobox do

A

Codes for a specific sequence of 60 amino acids, within the synthesised protein, called a homeodomain

60
Q

The homeodomain

A

What the homeobox codes for
-folds into a specific shape consisting of three alpha helices
-2nd and 3rd helix create a helix turn helix

61
Q

Helix turn helix

A

2nd and 3rd alpha helices are connected by a short loop of amino acids

62
Q

Purpose of the helix turn helix

A

Allows the protein to bind to DNA and regulate the transcription of nearby genes
- Proteins that contain homeodomains are therefore transcription factors

63
Q

Purpose of homeodomain

A

Binds to the DNA and acts as a transcription factor and therefore regulates other genes being switched on

64
Q

What are hox genes

A

Homeobox genes in animals
- Involved in the formation of anatomical features in the correct locations of the body plan

65
Q

What kind of animals are hox genes found in and what does this suggest

A

Bilaterian animals = suggest hox genes must have existed in the common ancestor of all bilaterians

66
Q

How are the hox genes arranged

A

Several hox genes are found next to each other on a chromosome and are arranged in clusters

67
Q

What is a homeotic mutation

A

When a hox gene is mutated body parts develop on the wrong places of the body

68
Q

When are hox genes expressed

A

In early embryonic development along the anterior-posterior (head-tail) axis of the organism

69
Q

Spatial linearity

A

The order of the genes on the chromosome matches the expression pattern along the embryo
- the genes for the head are found first

70
Q

Temporal order

A

The genes for the head are expressed first

71
Q

Collinearity

A

Spatial linearity + temporal order
-Scientists do not yet understand the importance of this for hox genes

72
Q

What happens when each hox gene is expressed

A

It encodes a specific hox protein that acts as a transcripton factor

73
Q

What do activated genes promote

A

The correct development of each body segment by regulating mitosis, apoptosis and cell differentiation

74
Q

How are hox genes regulated

A

Gap genes and pair rule genes
-These are then regulated by maternally supplied mRNA from the egg cytoplasm

75
Q

How does a STOP codon work

A

Does not for an amino acid/ no matching tRNA

76
Q

Why does meiosis have two stages

A

-To halve chromosome no. = diploid to haploid
-Separate homologous pairs (of chromosomes) and sister chromatids
-Chromosomes are two chromatids to start

77
Q

Why does the homeotic gene not really mutate

A
  • Genes are very important
    -Mutation would have large effects
    -Many other genes affected
    -Mutation = lethal

Module 6 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions