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Biology A2 Rafa > 6.1 Cellular Control > Flashcards

6.1 Cellular Control Flashcards

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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
Q

How do we reduce chance of point mutations?

A

Most amino acids have more than one triplet code

26
Q

Example of result of missense mutation

A

Sickle cell anaemia is result of mutation on sixth base triplet of gene for beta polypeptide chains of haemoglobin

27
Q

What is a mutation?

A

Random change to genetic material

28
Q

Effects of indel mutation?

A

frameshift, all of the codons change

29
Q

Explain expanding nucleotide repeats?

A

a type of insertion, extra amino acid added usually at meiosis, eg CAG CAG CAG when too many = huntingtons

30
Q

What is inversion?

A

a type of substitution where part of DNA inverts itself and reattaches in opposite direction

31
Q

Which organism’s lac operon do we study?

A

E. coli bacterium, normally respires glucose, when no glucose it metabolises lactose

32
Q

What does lac Z code for?

A

beta-galactosidase

33
Q

What does lac Y code for?

A

lactose permease

34
Q

What are the structural genes?

A

lac Z and lac Y

35
Q

What binds to the promoter region?

A

RNA polymerase

36
Q

What do transcription factors do?

A

Control which genes of a cell are turned on or off

37
Q

How do transcription factors work?

A

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
Q

What do the sites of transcription factors do?

A

Bind to specific sequences of DNA bases (promoter regions

39
Q

How can the action of transcription factors be regulated by other molecules example?

A

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
Q

What is apoptosis?

A

programmed cell death

41
Q

define conserved

A

has remained in all descendent species throughout evolutionary history

42
Q

Define homeobox sequence

A

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
Q

Define Hox genes

A

subset of homeobox genes, found only in animals; involved in formation of anatomical features in correct locations of body plan

44
Q

Whats a homeodomain sequence?

A

60 amino acid sequence made of the homeobox sequence (refers to protein)

45
Q

What does the homeodomain sequence do?

A

Binds DNA and regulates transcription of adjacent genes (transcription factor)

46
Q

Characteristic shape of homeodomain sequence?

A

Helix-turn-helix

47
Q

How are Hox genes arranged?

A

In clusters and each cluster contains up to 10 genes

expressed in order along the anterior-posterior axis of the developing embryo

48
Q

What is colinearity?

A

Spatial set up of genes is conserved when we express genes in organism

49
Q

What do Hox genes activate?

A
  • mitotic division
  • apoptosis
  • cell migration
  • cell cycle
50
Q

How are Hox genes regulated?

A

hierarchy of control

-maternally supplied mRNA in egg cytoplasm regulate gap genes which regulate pair-rule genes which regulate Hox genes

51
Q

What is the Hayflick constant?

A

the number of times a body cell can divide before dying (around 50)

52
Q

Stages of apoptosis

A
  • cytoskeleton breakdown
  • cytoplasm becomes dense with highly packed organelles
  • BLEBBING
  • chromatin condenses, nuclear envelope and DNA break apart
  • vesicle formation
53
Q

When does apoptosis happen?

A

when genes regulating the cell cycle respond to stimuli , eg DNA replication making mistakes or NO

54
Q

Example of why apoptosis important?

A

Separating webbed fingers

Biology A2 Rafa (14 decks)

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