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A Level > Biology 6.1 > Flashcards

Biology 6.1 Flashcards

1
Q

Point mutation

A

The bases substitute

Are made up of silent, missense and nonsense mutations

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2
Q

Indel mutation

A

Bases are inserted and deleted
This causes frameshift
The bases aren’t inserted in groups of 3

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3
Q

Silent mutation

A

The base trirplet changes but still codes for the same amino acid
This is because the code is degenerate

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4
Q

Missense mutation

A

The base triplet changes and codes for a different amino acid

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5
Q

Nonsense mutation

A

The base triplet changes and codes for a stop/termination triplet

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6
Q

What are transcription factors?

A

They control when genes are on or off

They bind to a specific promoter region

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7
Q

What are introns?

A

They are non coding regions in primary mRNA

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8
Q

What are exons?

A

Coding regions in mRNA

They are expressed

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9
Q

What happens in post transcriptional gene regulation?

A

The mRNA in edited and the introns are removed by splicing

Then the exons are joined by the endonuclease enzyme

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10
Q

What are homeotic genes?

A

Genes that control anatomical development

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11
Q

What are homeobox genes?

A

They are 180 base pairs that code for the homeodomain sequence

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12
Q

What is the homeodomain sequence?

A
  • A strand of 60 amino acids that act as transcription factors
  • They bind to promoter or enhancer regions and promote or inhibit transcription of the homeotic genes
  • They are made up of 3 alpha helices
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13
Q

What are hox genes?

A
  • Genes that are only in animals
  • Highly conserved
  • They control where body parts grow along anterior-posterior axis
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14
Q

What is colinearity?

A

Sequential temporal order of gene expression

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15
Q

How are hox genes regulated?

A

Regulated by gap genes and pair rule genes

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16
Q

What is the lac operon?

A

An operon that works in E. coli bacteria, that can produce enzymes needed to break down lactose if glucose isn’t present

17
Q

What enzymes does the lac operon code for?

A

Lactose permease

Beta galactosidase

18
Q

What happens at the lac operon when glucose is present?

A
  • Regulatory Gene (I) codes for a repressor protein
  • THe repressor protein binds to operator
  • THis means RNA polymerase can’t bind to promoter region
  • No MRNA made so genes Lac Z and Lac Y are off
19
Q

What are the genes that code for the enzymes?

A

Lac Y and Lac Z

20
Q

What happens at the lac operon when only lactose is present?

A
  • Lactose binds to repressor protein
  • This means the repressor protein can’t bind to operator
  • RNA polymerase can bind to promoter
  • MRNA is made so enzymes break down lactose
21
Q

How are proteins activated?

A
  • Signalling molecule binds to receptor
  • The G protein activated
  • Adenyl cyclase enzymes turn ATP to cAMP
  • CAMP activates PKA
22
Q

What does PKA do?

A
  • Catalyses phosphorylation of enzymes
  • Hydrolyses ATP
  • Phosphorylates CREB which is a transcription factor
23
Q

How does apoptosis work?

A
  • Cytoskeleton breaks down
  • Blebs (small protrusions) form
  • DNA/ nuclear envelope break down
  • Cell turns into vesicles
  • Phagocytes ingest vesicles
24
Q

How is apoptosis controlled?

A

By signalling molecules

  • Cytokines
  • Hormones
  • Growth factors
  • Nitric oxide
25
Q

How does nitric oxide control apoptosis?

A
  • It makes the inner mitochondrial membrane more permeable so the proton gradient dissipates
  • Proteins are released
  • The proteins bind to apoptosis inhibitor proteins so apoptosis occurs
26
Q

What is a promoter?

A

DNA sequence that RNA polymerase binds to

Located before the structural gene

27
Q

What is the operator?

A

DNA sequence that transcription factors bind to

28
Q

What are factors that increase the rate of transcription called?

A

Activators

29
Q

What are factors that decrease the rate of transcription called?

A

Repressors

30
Q

What does the regulatory gene do?

A

Codes for the repressor or enhancer

31
Q

What causes apoptosis?

A

DNA damage during the cell cycle
Stress due to lack of nutrient availability
Attack by a pathogen

32
Q

Why might mutations have a neutral effect on a proteins function?

A

Degenerate sequence so codes for the same amino acid
That amino acid could be far from the active site/not involved in its function
Could code for an amino acid that is chemically similar

33
Q

What is a beneficial mutation?

A

Bacteria becoming resistant to antibiotics

34
Q

What is a harmful mutation?

A

Cyctic fibrosis where the gene coding for CFTR protein mutates, leading to excess mucus production in the lungs

A Level (25 decks)

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