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Biology A2 Rafa > 6.1 Cellular Control > Flashcards

6.1 Cellular Control Flashcards

1
Q

What are the two main classes of gene mutation?

A

Point mutation

Indel mutation

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2
Q

What are the three types of point mutation

A

silent
missense
nonsense

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3
Q

What is a point mutation?

A

one base pair replaces another

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4
Q

what is an indel mutation?

A

one or more nucleotides are inserted or deleted from a length of DNA

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5
Q

Describe silent mutations

A

change to triplet, where triplet still codes for the same amino acid

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6
Q

Describe missense mutations

A

A change to the base triplet sequence that leads to a change in the amino acid sequence in a protein

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7
Q

Describe nonsense mutations

A

The alteration of a base triplet so that it becomes a stop codon

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8
Q

Define exon

A

the coding, or expressed,region of DNA

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9
Q

Define intron

A

The non-coding region of DNA

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10
Q

Define operon

A

A group of genes that function as a single transcription unit; first identified in prokaryotic cells

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11
Q

Define transcription factor

A

protein or short non-coding RNA that can combine with a specific site on a length of DNA and inhibit or activate transcription of a gene

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12
Q

What two enzymes does lactose induce the production of?

A

lactose permease

beta-galactosidase

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13
Q

What does lactose permease do?

A

allows lactose to enter the bacterial cell

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14
Q

What does beta-galactosidase do?

A

hydrolyses lactose to glucose and galactose

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15
Q

What is the lac operon?

A

length of DNA, containing an operator region (lacO) next to structural genes(lacZ and lacY) that code for beta galactosidase and lactose permease respectively

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16
Q

How to remember lac operon

A

IPOZY

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17
Q

What is the promoter region?

A

RNA polymerase binds to begin transcription

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18
Q

What are the control sites in the lac operon

A

operator region and promoter region

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19
Q

What is the regulatory gene?

A

I, codes for repressor protein, lacI, when it is expressed, the repressor protein binds to the operator, preventing RNA polymerase from binding to the promoter region.

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20
Q

What changes to the lac operon when lactase is added?

A

binds to LacI repressor protein molecules, altering the shape of LacI repressor protein, preventing it from binding to the operator.

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21
Q

What enzyme is involved in removing introns?

A

Endonuclease

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22
Q

What is post-transcriptional gene regulation?

A 
primary mRNA (with both introns and exons) are edited and introns are removed.
Exons are joined together
23
Q

What is post-translational gene regulation?

A

Activation of proteins

Many enzymes are activated by being phosphorylated

24
Q

What controls gene expression at a transcriptional level?

A

Transcription factors

25
How do we reduce chance of point mutations?
Most amino acids have more than one triplet code
26
Example of result of missense mutation
Sickle cell anaemia is result of mutation on sixth base triplet of gene for beta polypeptide chains of haemoglobin
27
What is a mutation?
Random change to genetic material
28
Effects of indel mutation?
frameshift, all of the codons change
29
Explain expanding nucleotide repeats?
a type of insertion, extra amino acid added usually at meiosis, eg CAG CAG CAG when too many = huntingtons
30
What is inversion?
a type of substitution where part of DNA inverts itself and reattaches in opposite direction
31
Which organism's lac operon do we study?
E. coli bacterium, normally respires glucose, when no glucose it metabolises lactose
32
What does lac Z code for?
beta-galactosidase
33
What does lac Y code for?
lactose permease
34
What are the structural genes?
lac Z and lac Y
35
What binds to the promoter region?
RNA polymerase
36
What do transcription factors do?
Control which genes of a cell are turned on or off
37
How do transcription factors work?
They slide along a part of DNA and bind to specific promoter regions, aid or inhibit the attachment of RNA polymerase to DNA and activate or suppress transcription of the gene
38
What do the sites of transcription factors do?
Bind to specific sequences of DNA bases (promoter regions
39
How can the action of transcription factors be regulated by other molecules example?
e. g. oestrogen... - oestrogen diffuses through plasma membrane - binds to complementary site on transcription factor - changes shape of transcription factor and activates it - goes to nucleus through nuclear pore and activates transcription usually increasing affinity of RNA polyermase to promoter region
40
What is apoptosis?
programmed cell death
41
define conserved
has remained in all descendent species throughout evolutionary history
42
Define homeobox sequence
sequence of 180 base pairs (excluding introns) found within genes that are involved in regulating patterns of anatomical development in animals, fungi and plants
43
Define Hox genes
subset of homeobox genes, found only in animals; involved in formation of anatomical features in correct locations of body plan
44
Whats a homeodomain sequence?
60 amino acid sequence made of the homeobox sequence (refers to protein)
45
What does the homeodomain sequence do?
Binds DNA and regulates transcription of adjacent genes (transcription factor)
46
Characteristic shape of homeodomain sequence?
Helix-turn-helix
47
How are Hox genes arranged?
In clusters and each cluster contains up to 10 genes | expressed in order along the anterior-posterior axis of the developing embryo
48
What is colinearity?
Spatial set up of genes is conserved when we express genes in organism
49
What do Hox genes activate?
- mitotic division - apoptosis - cell migration - cell cycle
50
How are Hox genes regulated?
hierarchy of control | -maternally supplied mRNA in egg cytoplasm regulate gap genes which regulate pair-rule genes which regulate Hox genes
51
What is the Hayflick constant?
the number of times a body cell can divide before dying (around 50)
52
Stages of apoptosis
- cytoskeleton breakdown - cytoplasm becomes dense with highly packed organelles - BLEBBING - chromatin condenses, nuclear envelope and DNA break apart - vesicle formation
53
When does apoptosis happen?
when genes regulating the cell cycle respond to stimuli , eg DNA replication making mistakes or NO
54
Example of why apoptosis important?
Separating webbed fingers

Biology A2 Rafa (14 decks)

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