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Biology set 3 > 6.1.1 - Cellular control > Flashcards

6.1.1 - Cellular control Flashcards

1
Q

Characteristics of genetic code

A

Universal
Triplet code
Degenerate
Non-overlapping

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2
Q

Properties of DNA

A

Introns

Exons

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3
Q

Introns

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

Regulatory sequences

A

Parameter regions
Terminator rehions
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

Genes that code for regular proteins

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8
Q

Mutagens

A

Chemical, physical, or biological agents which cause mutations e.g. viruses, radiation

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9
Q

Where can genes be turned on or off

A

Transcriptional
Post-transcriptional
Translational
Post-translational

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10
Q

When does up/down regulation occur

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

Genes

Chromosomal

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15
Q

Point mutations

A

Mutations that occur at a spp point

Insertion
Substitution
Deletion

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16
Q

Effects of point mutations of proteins

A

Silent
Missense
Nonsense

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17
Q

Chromosomal mutations

A

Deletion
Duplication
Translocation

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18
Q

Insertion mutations

A

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

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19
Q

Substitution mutation

A

Occurs when a base pair is substituted for another

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20
Q

Deletion mutation

A

Occurs when a base pair is deleted from the DNA sequence

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21
Q

Frameshift

A

A mutation caused by the addn. or deln. of a base pair(s) resulting in the translation of the genetic code from an unnatural reading frame from the point mutation to the end of the gene

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22
Q

Silent mutations

A

Change in the DNA sequence that results to the change in nucleotide base pairs having no subsequent effect on on the amino acid produced

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23
Q

Missense mutations

A

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

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24
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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25
Class of mutations
Beneficial - depends on environment Neutral - No effect on chances of survival Disadvantageous - Causes genetic diseases, lessens chances of survival
26
Histones
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
27
Chromatin
Complex of DNA and proteins that condense to form chromosomes within the nucleus of eukaryotic cells
28
Euchromatin
Lightly packaged DNA; RNA polymerase can access the bases to transcribe the genes --> genes can be turned on
29
Heterochromatin
Tightly packaged DNA; RNA polymerase cannot access the bases to transcribe the genes so they are turned off
30
Promoter regions
Region of DNA that acts as the binding site for RNA polymerase to start transcription Intron Usually upstream
31
Operator regions
Short region of DNA that is close to the promoter region | Interacts w/ regulatory proteins that controls the transcription of operons
32
Downstream
To the right
33
Upstream
To the left
34
Operon
Functioning unit of DNA containing a group of structural genes expressed together Controlled by one promoter Only found in prokaryotes
35
How is gene expression regulated in operons
Transcription factors bind
36
Transcription factors
Coded for by regulatory genes Proteins which affects rate of transcription Activates or inhibits transcription of DNA by binding to spp DNA sequences
37
Repressor protein
A protein that binds to DNA/RNA inhibiting transcription by binding to the operator
38
Gene expression
Production of proteins from a genome
39
Control of gene expression
Whether genes are turned on or off
40
Why is the control of gene expression necessary
In specialisation and differentiation of cells Increasing/ decreasing complexity Prevent vital resources being wasted
41
Why is gene expression more complex on eukaryotes
Have to respond to changes in the internal and external environments Histones - DNA not exposed, genes expression is harder Prokaryotes don't have histones
42
Housekeeping genes
Genes that code for proteins which are necessary for reactions in metabolic pathways and are constantly required (enzymes)
43
Who has only exons
Prokaryotes and eukaryotes without jaw bones | Jaw boned eukaryotes have introns and exons
44
Terminator region
Does not code for protein Regulatory site RNA polymerase is released to stop trancription
45
RNA-coding sequence
Genes turn into mRNA | Has both introns and exons but introns are removed from premature mRNA during splicing to form mature mRNA
46
Methods to regulate gene expression at transcriptional level
Heterochromatin Histone modification Transcription factors
47
Heterochromatin as a method of gene expression
Transcription of tightly wound DNA isn't possible as RNA polymerase cannot access the bases Occur in interphase so correctproteins are made for cell division Prevents protein synthesis during cell division (v. energy consuming)
48
Histone modification
Histones are +vely charged and DNA. -vely charged --> attraction Modify charges to change degree of packaging Acetyls and phosphates reduce +ve charge so transcription happens Methyls increase +ve charge so transcription doesn't occur
49
Transcription factors as a method of gene expression
Control rate of transcription by binding to spp DNA sequences Regulate genes to make sure they are expressed correctly Work alone or w/ others as an activator, repressor or recruiter of RNA polymerase
50
Regulating gene expression at the post transcriptional level
RNA processing RNA editing Happen simultaneously
51
RNA processing
Pre-mRNA is modified --> mature-mRN A binds to ribosme and code for synthesis Cap is added at 5' and tail at 3' Stabilises mRNA and delays degradation in cytoplasm, aids binding Splicing and the addn. of the cap and tail occur in the nucleus
52
RNA editing
Some mRNA can be changed through base pair add., deln. or subn. Same effects as point mutations and results in synthesis of diff proteins w/ diff function s Increases range of proteins that can be produced from one mRNA strand
53
Regulating gene expression at the translational level
Degradation of mRNA | Binding of inhibitory proteins
54
Degradation of mRNA
More resilient the molecule, the longer it lasts, more translation
55
Binding of inhibitory proteins
Prevents mRNA binding to ribosomes and the synthesis of proteins
56
Regulation of gene expression at the post translational level
Protein activation
57
Protein activation
Adding non protein groups e.g. carbs, phosphates Modifying AA and formation of bonds e.g. disulphide bridges (3' structure) Folding/ shortening proteins (2' structure) Modification by cAMP
58
Control sites
Operator region and promoter region
59
Beta galactoside
An enzyme that catalyses the hydrolysis of lactose to glucose and galactose
60
Lactose permease
A protein that transports lactose into the cell
61
Lac i
Regulatory gene Codes for repressor protein (transcription factor) Always transcribed
62
Lac p
Promoter region | Rna polymerase binds here
63
Lac o
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
64
Lac z
Structural gene codes for beta galactoside
65
Lac y
Structural gene that codes for lactose permease
66
Lac operon
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
67
Mechanism of apoptosis
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
68
Uses of apoptosis
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)
69
Somatic cell
Body cell
70
Germ line cells
Gametes
71
Germline mutations
Mutations in gametes so can cause genetic diseases and are passed on
72
Somatic mutations
Not inherited but can cause ageing and cancer | Result of mutations in normal diploid cells
73
Homeobox genes
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
74
Homeotic genes
Set of genes that control morphology
75
Homeodomain
Section of the protein coded for by the homeobox sequence (60 AA)
76
Hox genes
Sub type of homeobox genes Only found in vertebrates and animals Found in clusters on chromosomes Controls body plans and morphology
77
What do Hox genes code for
A group of TF's that bind to certain sections of DNA allowing transcription of genes associated w/ the development of an organism during its embryonic stage to form a mature body plan
78
What does a mutation of a Hox gene lead to
Diff body plan
79
What ensures features are expressed correctly
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
80
Why are Hox genes highly conserved
V. important Mutations alter body plans Mutations are selected against
81
Polypeptides that control the physical development of an organism
Structural proteins Enzymes used in metabolic pathways Hormones Receptor proteins

Biology set 3 (25 decks)

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