Biology > Cellular Control > Flashcards

Cellular Control Flashcards

(51 cards)

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1
Q

What is a mutuation?

A

An unpredicatable change in the genetic material of an organism

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2
Q

When can mutations occur?

A

During meisosis, leading to mutations in chromosomes
DNA replication, leads to mutations in gene

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3
Q

What is substitution?

A

Single nucleotide base replaced with another

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4
Q

What is the effect of subsitution?

A

Change in amino acid, premature stop codon, or may have no change if not in coding region

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5
Q

What is deletion?

A

One or more nucleotide bases removed from sequence

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6
Q

What is the effect of deletion?

A

May change or remove amino acid from sequence

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7
Q

What is insertion?

A

One or more nucleotides added to sequence

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8
Q

What is the effect of insertion?

A

Alter all following codons, alters amino acids coded for

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9
Q

What is an example of a physical mutagen?

A

Ionising radiation (alpha, beta, gamma)

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10
Q

What is an example of a chemical mutagen?

A

Mustard gas, tar in tobacco smoke

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11
Q

What is an example of a biological mutagen?

A

Viruses, base analogs

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12
Q

What is a mutagen?

A

Agents which lead to mutations, increase the frequency

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13
Q

What is chromosomal deletion?

A

Loss of all or part of a chromosome

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14
Q

What is chromosomal duplication?

A

Produces an extra copy of all or part of a chromosome

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15
Q

What is chromosomal inversion?

A

Reverses direction of parts of a chromosome

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16
Q

What is chromosomal translocation?

A

Part of one chromosome breaks off and attaches to another

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17
Q

What is transcriptional control?

A

Genes can be turned on and off

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18
Q

What is post-transcriptional modification?

A

mRNA can be modified
Involves splicing of pre-mRNA into mRNA and RNA editing

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19
Q

What is translational control?

A

mRNA used as template for amino acid sequence, can be stopped and started

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20
Q

What is post-translation modification?

A

Protein can be modified to alter their function

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21
Q

How is Chromatin involved in transcriptional control?

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A

DNA arranged around proteins called histones
Heterochromatin: during replication, DNA tightly wound and transcription prevented
Euchromatin: During interphase DNA is less tightly wound and the genes are more accessible for transcription

22
Q

When does transcriptional control occur?

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A

During interphase, can’t be done during mitosis/meiosis
Energy needed for transcription, means enzymes and other factors are ready for nuclear division or possible differentiation

23
Q

What does epigenetics mean?

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A

Control of gene expression through modification of DNA, study of changes in organised caused by modification of gene expression rather than alteration of genetic code itself

24
Q

What is an operon?

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A

A unit made of linked genes which is thought to regulate other genes responsible for protein synthesis

25
How is the lac operon used in E.coli?
E.coli preferentially respire glucose Has genes necessary to respire lactose: usually switched off, no need to produce is not needed, waste energy and resources Presence of lactose: switched on, allows transcription of genes needed to metabolise lactose, switched on if glucose low, lactose high
26
What are the three genes expressed as part of lac operon?
Beta galactosidase, lactose permease, transacetylase
27
What is the role of beta galactosidase in the lac operon?
Enzyme that breaks down lactose into glucose and galactose
28
What is the role of lactose permease in the lac operon?
Membrane protein needed to increase uptake for lactose
29
What is the role of transacetylase in the lac operon?
Transfers acetyl from acetyl CoA to Beta galactoside, coded by a gene (lacA), precise function not understood
30
What happens during the processing of mRNA into mature mRNA?
Methylated cap added to 5' end and a poly A tail added to 3' end, delays degradation of mRNA Splicing: non-coded regions called introns are released
31
What is RNA editing?
Mechanism to increase number of different proteins available without the need to increase the number of genes in the genome
32
What occurs during RNA editing?
-Base addition, deletion or substitution -Results in synthesis of different proteins which could have different function -Increases range of proteins from one mRNA, saves transcription energy
33
How is translation controlled?
Longer mRNA lasts, the more it can be translated, more protein made Degreadation of mRNA can be made quicker or slower to control how much protein made Inhibitory proteins prevent mRNA from binding to ribosomes mRNA have inititation factors which help mRNA bind to ribosomes, can be activated at later date
34
What are protein kinases?
Enzymes that catalyse phosphorylation of proteins. Changes tertiary structure and so their function Protein kinases can be activated by cAMP
35
What modifications happen to proteins themselves during post-translational control?
-Addition of non-protein groups: carbs, lipids -Modifying amino acids and formation of bonds -Folding or shortening proteins
36
What is a homeobox gene?
Genes that determine how an organisms body develops as it grows from a zygote to a complete organism, control anatomical development (morphogenesis), means correct structures grow in the correct location
37
What is a homeobox sequence?
A stretch of 180 DNA base pairs, coding for a 60 amino acid sequence
38
What is a homeodomain sequence?
A 60 amino acid sequence within a protein that acts as a transcriptional factor for other genes, working with other genes to turn them off
39
What are Hox genes?
A group of homeobox genes only seen in animals, these genes control the body plan (which was is up), found in four clusters in mammals If mutated, abnormalities occur during development
40
What is radial symmetry?
Have no left or right sides, only top and bottom Jellyfish
41
What is bilateral symmetry?
Seen in most animals, left and right and head and tail
42
What is asymmetry?
No lines of symmetry, seen in sponges
43
What is apoptosis?
Programmed cell death during development of an organism, can occur during the development of an embryo or at crucial metamorphosis stages
44
How is apoptosis different to necrosis?
Quick process, is orderly and planned unlike necrosis, which occurs following the release of hydrolytic enzymes following trauma to cells
45
What are the uses of apoptosis?
Erase errors Shape/metamorphasis
46
What is stage 1 of apoptosis?
Enzymes break down cytoskeleton Cytoplasm becomes dense, with organelles tightly packed
47
What is stage 2 of apoptosis?
Cell surface membrane changes, small bits called blebs form Chromatin condenses Nuclear membrane breaks and DNA breaks up into fragments
48
What is stage 3 of apoptosis?
Cell breaks up into vesicles Vesicles taken up by phagocytosis Cellular debris is disposed of and does not damage any other cells or tissues
49
How can the environment affect the expression of regulatory genes?
Change in internal/external environment Stress: condition produces when homeostatic balance disturbed -External factors: change in temperature, light intensity -Internal factors, change in hormones or psychological stress Greater impact during growth
50
How can drugs affect the expression of regulatory genes?
Eg thalidomide Given to pregnant women to treat morning sickness, found it prevented normal Hox gene expression, babies born with shortened limbs
51
Which kingdoms use homeobox genes?
Animalia, Plants, and fungi
Biology
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