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Big Yerp > Unit 6 - Genetics of living systems > Flashcards

Unit 6 - Genetics of living systems Flashcards

1
Q

Characteristics of genetic code

A

Universal
Triplet code
Degenerate
Non-overlapping

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2
Q

2 regions of DNA

A

Introns (non-codingh)
exons (coding)

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3
Q

Introns

charatceristics

A

Sections of DNA that do not code for a polypeptide
Regulatory sequences
Acts as a buffer for mutations

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4
Q

examples of regulatory sequences

A

Promoter regions
Terminator regions
Operator regions (prokaryotes)

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5
Q

Exons

A

Sections of DNA that code for polypeptides

Regulatory or structural genes

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6
Q

Regulatory genes

A

Genes that code for proteins used in DNA regulation

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7
Q

Structural genes

A

codes for proteins not used in regulations

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8
Q

Mutagens

give examples

A

Chemical, physical, or biological agents which cause mutations e.g. viruses (viral DNA inserts itself into the genome), radiation (Breaks one or both DNA strands)

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9
Q

Where can genes be turned on or off

what are the levels of control

A

Transcriptional
Post-transcriptional
Translational
Post-translational

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10
Q

When does up/down regulation occur

what does this do

A

Post trasncriptional
Translational
Post translational

Either increases/ decreases rate of protein synthesis

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11
Q

When are proteins modified

A

Translational
Post translational

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12
Q

Where are ribosomes assembled

A

Nucleolus

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13
Q

Why is there a ribosomal groove

A

So mRNA can be read for transcription

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14
Q

Types of mutations

A

gene
chromosomal

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15
Q

Define Point mutations

what are 3 types

A

Mutations that occur to a single nucleotide base

Insertion
Substitution
Deletion

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16
Q

what effects can point mutations have on proteins

A

Silent
Missense (different amino acid coded for)
Nonsense

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17
Q

Insertion mutations

A

Addn. of one or more nucleotide base pairs into a DNA sequence

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18
Q

Substitution mutation

A

Occurs when a base pair is substituted for another

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19
Q

Deletion mutation

A

Occurs when a base pair is deleted from the DNA sequence

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20
Q

Frameshift

A

a genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the reading frame so the sequence is read diffrently

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21
Q

Silent mutations

A

A change in the DNA sequence that results in a change to the nucleotide base pairs but has no subsequent effect on on the amino acid produced

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22
Q

Missense mutations

A

A single nucleotide change leads to a different codon and therefore a different AA

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23
Q

Nonsense mutations

A

Change in nucleotide sequence that leads to one of codons being converted to a terminator codon so the protein produced is truncated

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24
Q

Class of mutations

A

Beneficial - depends on environment
Benign - No effect on chances of survival
Damaging - Causes genetic diseases, lessens chances of survival

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25
Q

Histones

A

Basic proteins that associate w/ DNA in the nucleus and help to condense the DNA into a smaller volume
Little balls in which DNA wraps around

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26
Q

Chromatin

A

Complex of DNA and proteins that condense to form chromosomes within the nucleus of eukaryotic cells

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27
Q

Euchromatin

A

Loosley packaged DNA
RNA polymerase can access the bases to transcribe the genes –> genes can be turned on

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28
Q

Heterochromatin

A

Tightly packaged DNA
RNA polymerase cannot access the bases to transcribe the genes
so they are turned off

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29
Q

Promoter regions

what type of sequence is it

A

Region of DNA that acts as the binding site for RNA polymerase to start transcription
Intron
Usually upstream

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30
Q

what are operator regions

A

Short region of DNA, close to the promoter region that along with regulatory proteins control transctription of operons

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31
Q

Downstream

A

To the right

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32
Q

Upstream

A

To the left

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33
Q

Operon

A

group of genes controlled by one promotor and are expressed at the same time
Only found in prokaryotes

34
Q

How is gene expression regulated in operons

A

Transcription factors bind to them

35
Q

Transcription factors

  • what codes for them
  • what is their function, how do they carry this out
A

Coded for by regulatory genes
Proteins which affects rate of transcription
Activates or inhibits transcription of DNA by binding to promoter region w/ RNA polymerase or blocking the promoter region

36
Q

Repressor protein

A

A protein that binds to DNA or RNA, inhibiting transcription by binding to the operator sequeunce

37
Q

Gene expression

A

Production of proteins from a genome

38
Q

Control of gene expression means what

A

Whether genes are turned on or off

39
Q

Why is the control of gene expression necessary

A

to diffrentiate and specalise cells

Prevent vital resources being wasted

40
Q

Why is gene expression more complex on eukaryotes

A

Have to respond to changes in the internal and external environments

DNA wrapped around histones so not exposed = gene expression is harder, prokayoytes dont have these

41
Q

Housekeeping genes

A

Genes that code for proteins which are necessary for reactions in metabolic pathways and are constantly required (enzymes)

42
Q

Who has only exons

A

Prokaryotes and eukaryotes without jaw bones

Jaw boned eukaryotes have introns and exons

43
Q

Terminator region

A

Regulatory site
RNA polymerase is released to stop trancription

44
Q

what are RNA-coding sequence

A

Genes that code for mRNA

Has both introns and exons but introns are removed from premature mRNA during splicing to form mature mRNA

45
Q

Methods to regulate gene expression at transcriptional level

A

Histone modification
Transcription factors

46
Q

How are histones modified
How do the modifications affect DNA packaging

A

Histones are +vely charged and DNA. -vely charged –> attraction
change to charges change degree of packaging
Acetylation and phosphorylation reduce +ve charge so DNA binds more loosely = transcription happens
Methylation increase +ve charge so transcription doesn’t occur as DNA binds more tightly

47
Q

How do Transcription factors act as a method of gene expression regulation

A
  • activate or repress RNA polymerase
48
Q

Methods of gene regulation at the post-transcriptional level

A

RNA processing
RNA editing
siRNA

49
Q

what is the process of RNA processing
where does it occur in cell

A

Pre-mRNA is spliced to remove intrones, mature-mRNA forms

modified nuclotide cap is added at 5’ and adenine tail at 3’ ^Stabilises mRNA and prevents degradation

occur in the nucleus

50
Q

what is RNA editing

A

base pair add., deln. or subn in mature-mRNA, which results in different proteins
multiple proteins can be made from one mRNA strand

51
Q

what are the methos of gene expression regulation at the translational level

A

Degradation of mRNA
Binding of inhibitory proteins
Protein kinases

52
Q

Degradation of mRNA

A

More resilient the molecule, the longer it lasts in cytoplasm, more translation

53
Q

Binding of inhibitory proteins

A

Occurs when protein is produced in wrong location or substrate is not available

54
Q

Regulation of gene expression at the post translational level

A

Protein activation - allows protein to carry out its function

55
Q

Protein activation

A

Occurs in Golgi
Adding non protein groups e.g. carbs, phosphates
Phosphorylation by protein kinases and ATP
Folding/ shortening proteins (2’ structure)
Modification by cAMP

56
Q

Control sites

A

Operator region and promoter region

57
Q

Beta galactoside

A

An enzyme that catalyses the hydrolysis of lactose to glucose and galactose

58
Q

Lactose permease

A

A protein that transports lactose into the cell

59
Q

Lac i

A

Regulatory gene
Codes for repressor protein (transcription factor)
Always transcribed

60
Q

Lac p

A

Promoter region

Rna polymerase binds here

61
Q

Lac o

A

Operator region of control site
Repressor protein binds here
When lactose is present causes a conformational change in repressor protein allowing it to bind to lactose instead

62
Q

Lac z

A

Structural gene codes for beta galactoside

63
Q

Lac y

A

Structural gene that codes for lactose permease

64
Q

Lac operon

A

Inducible operon (only occurs when lactose is present from diffusion through lactose channels )
Example of transcriptional regulation
Group of 3 genes involved in metabolism of lactose

65
Q

Mechanism of apoptosis

A

Cytoskeleton broken down by enzymes, loses function
Cell shrinks and the membrane blebs, chromatin condenses
Lysosomes release enzymes which break down cell components
Cell breaks up into membrane-bound fragments
Cell fragments are ingested and digested by phagocytic cells

66
Q

Uses of apoptosis

A

Morphogenesis - eliminating excess cells (webbed fingers)
Selection - eliminates non functional cells
Immunity - T killer eliminates dangerous cells (cancer)
Organ size - eliminates excess cells
Tissue remodelling - eliminates cells no longer need (breastfeeding)

67
Q

Somatic cell

A

Body cell

68
Q

Germ line cells

A

Gametes

69
Q

Germline mutations

A

Mutations in gametes so can cause genetic diseases and are passed on

70
Q

Somatic mutations

A

Not inherited but can cause ageing and cancer

Result of mutations in normal diploid cells

71
Q

Homeobox genes

A

Regulatory genes that contain a homeobox sequence (180 bp)
Highly conserved in animals, plants and fungi
Regulates mitosis and apoptosis in the embryonic stage
Control body plans of an organism

72
Q

Homeotic genes

A

Set of genes that control morphology

73
Q

Homeodomain

A

Section of the protein coded for by the homeobox sequence (60 AA)

74
Q

Hox genes

A

Sub type of homeobox genes
Only found in vertebrates and animals
Found in clusters on chromosomes
Controls body plans and morphology

75
Q

What do Hox genes code for

A

A group of TF’s that controls expression of structural genes associated w/ the development of an organism’s appendages during its embryonic stage to form a mature body plan

76
Q

What does a mutation of a Hox gene lead to

A

Diff body plan

77
Q

What ensures features are expressed correctly

A

Hox genes in a Hox cluster are activated in a particular order depending on where its found on the chromosome
This matches order genes are expressed along H to T
So structural genes are activated in a carefully coordinated sequence

78
Q

Why are Hox genes highly conserved

A

V. important
Mutations alter body plans
Mutations are selected against

79
Q

Polypeptides that control the physical development of an organism

A

Structural proteins
Enzymes used in metabolic pathways
Hormones
Receptor proteins

80
Q

Protein kinases

A

Activated by cyclic AMP and activate proteins through phosphorylation using ATP

81
Q

siRNA

A

Small interfering RNA - only needed when cell has made sufficient protein
Complementary base sequence to mRNA that’s to be degraded
Binds to mRNA and activates an enzyme that breaks it down
RNA nucleotides recycled to nucleus

Big Yerp (42 decks)

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