Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A2 Biology > The Control of Gene Expression > Flashcards

The Control of Gene Expression Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What does substitution mutation involve?

A

When one nucleotide in a section of DNA molecule is replaced by another nucleotide that has a different base.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What could be consequences of a substitution mutation?

A
  • substitution results in a different aa being produced meaning the protein may not function properly
  • results in a stop codon being transcribed meaning polypeptide coding is stopped prematurely
  • substitution means nothing changes as the genetic code is degenerate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens in a deletion mutation?

A

Involves the loss of a nucleotide base from a DNA sequence. The polypeptide chain is often different due to the frame shift and will change how most of the codons are being read
Less likely to have an effect if it occurs at the end of a sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens in addition mutation?

A

When a extra base is added into the sequence and this also causes a frame shift causing the codons after to change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does inversion mutation involve?

A

Involves a group of bases becoming deprecated from the DNA sequence and rejoining in the same position but in inverse order, so instead of AUG, it’s GUA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does duplication mutation involve ?

A

One or more of the bases are repeated which produces frame shift to the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does translocation mutation involve?

A

Group of bases become separated from the DNA sequence in one chromosome and becomes inserted into DNA sequence of another chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are mutagenic agents?

A

Something that can effect the rate of gene mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Examples of mutagenic agents

A

UV light, X rays, alpha and beta radiation and chemicals such as mustard gas and nitrogen gas and cigarette smoke and Benzene (inactivates tumour suppressor gene)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are stem cells?

A

Cells that have the potential to differentiate into different specialised cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are stem cells properties?

A

Self renewal- the ability to go through numerous cycles of mitosis while remaining undifferentiated
Potency- the capacity to differentiate into specialised cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are totipotent stem cells?

A

Found in embryos and can differentiate into all 216 or so cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are pluripotent stem cells?

A

Found in the embryos and differentiate into almost every cell types-ex. includes embryonic stem cells and fetal stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are multipotent stem cells?

A

Found in adults and can differentiate into a limited number of specialised cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are unipotent cells?

A

Can only differentiate into a single type of cell. Derived from multi-potent stem cells and are made in adult tissue (fetal stem cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are induced pluripotent stem cells?

A

These are unipotent stem cells from specialised animal cells by genetically altering them using INDUCING GENES and transcription factors to acquire characteristics of EMBRYONIC STEM CELLS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is therapeutic cloning?

A

Technique used to extract or produce and grow stem cells for the purpose of treating human disorders. For example; creating new skin for burn victims

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the role of transcription factors?

A

Protein that binds to the promotor region of a gene to either promote or inhibit transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do activators (transcription factors) work?

A

They move from the cytoplasm to the nucleus and bind to start of their target genes and helping RNA polymerase bind to the target gene and thus activating transcription

20
Q

How do repressors (transcription factors) work?

A

An inhibitor molecule can bind to a transcription factor where it binds to DNA and blocks that DNA polymerase so transcription is deactivated and gene is not transcribed

21
Q

How does oestrogen aid the action of a transcription factor?

A

Oestrogen binds to a complimentary active site on the transcription factor molecule called ERalpha.
The transcription factor as a result changes shape and thus releases the inhibitor molecule from the binding site
The transcription factor can now enter the nucleus and bind to a specific region of DNA where it will stimulate transcription

22
Q

What is epigenetics?

A

heritable changes in gene function without changing the base sequence of DNA

23
Q

What is an epigenome?

A

DNA and histones are covered in chemical which forms a second layer known as the epigenome. Determines the shape of the DNA-histone complex

24
Q

Examples of the effect of the epigenome?

A

It can keep inactive genes in a tightly packed arrangement- so it ensures they cannot be read
OR it unwraps active genes so DNA is exposed and can easily be transcribed.

25
Q

What does acetylation of histones do ?

A

This increases the +ve charges on the histones
increases their attraction to the phosphate group of DNA
the DNA-histone association is stronger makes DNA inaccessible to transcription factors so the gene is switched off

26
Q

What does methylation of DNA do?

A

It’s added to the cytosine bases and it inhibits transcription
preventing the binding of transcription factors to DNA
Prevents RNA polymerase from binding
So protein synthesis is prevented

27
Q

What’s the second thing that methylation of DNA can cause?

A

Methyl groups can attract proteins that condense the DNA-histone complex making DNA inaccessible to proteins

28
Q

Examples of the use of epigenetics?

A

Can be used in the diagnostic testing of cancers, arthritis and brain disorders. This can identify the level of DNA methylation and histone acetylation

29
Q

How does small interfering RNA work (siRNA) ?

A

Enzyme cuts the large double stranded molecules of RNA into siRNA.
One of these strands combines with an enzyme to form a siRNA-protein complex. siRNA complex is moved to mRNA pairs with complementary bases
then cuts it into smaller sections

30
Q

What is the effect of the siRNA attaching to the mRNA?

A

Cuts mRNA to smaller sections;
mRNA is no longer able to be translated into polypeptide;
gene is not expressed

31
Q

Similarities between benign and malignant tumours?

A

They can grow to a large size and can add pressure to blood vessels when they grow

32
Q

Differences between benign and malignant tumours?

A

malignant undergo metastasis, benign tumours do not due to adhesion molecules
Benign have a capsule surrounding them, malignant don’t.
Benign tumours can be removed by surgery alone whilst malignant tumours require chemotherapy as well

33
Q

What are proto-oncogenes?

A

These stimulate a cell to divide when growth factors attach to a protein receptor on the CSM. These activate genes that cells to divide.

34
Q

How can oncogenes be permanently activated?

A

Two ways: Receptor protein is permanently activated even in absence of growth factors or oncogene codes for growth factors that is produced in excessive amounts

35
Q

What is the effect of permanent activation of oncogenes?

A

uncontrollable cell division and as a result cancer develops

36
Q

What are tumour suppressor genes?

A

These slow down cell division, repair mistakes in DNA and tell cells when to die DNA cannot be repaired- apoptosis

37
Q

What happens if tumour suppressor genes becomes mutated?

A

Gene is inactivated
it stops inhibiting cell division
leads to uncontrollable cell division

38
Q

How does hypermethylation of the tumour suppressor gene lead to cancer?

A

More methyl groups are added to promotor region and prevents transcription
Therefore protein is not made and tumour suppressor gene is not expressed
Therefore promotor region of tumour suppressor gene is inactivated
This gene inactivation leads to uncontrollable cell division

39
Q

How does oestrogen concentrations cause breast cancer?

A

if the gene that oestrogens acts on a gene and removes one that controls cell division and growth, the gene will be inactivated and would produce a tumour

40
Q

where do multipotent stem cells usually develop?

A

usually develop into the stem cells in the bone marrow

41
Q

Describe the process of genetic fingerprinting (6 points)

A
  1. DNA sample is put through PCR to make large sample
  2. Sample is cut R-endonuclease
  3. Gel electrophoresis seperates DNA fragments by length
  4. Southern Blotting technique used
  5. DNA is made single stranded using chemicals
  6. DNA probe is attached which has complimentary base sequence to tandem repeats
  7. Every person has unique DNA fingerprint
42
Q

How does PCR work?

A
  1. Heat to 95c to break H bonds between DNA strands to separate the two strands
  2. Mixture is cooled to 55c causing primers to bind to complimentary bases
  3. Increase temp to 72c to allow DNA polymerase to add complementary nucleotides
  4. Cycle is repeated to 25-30 times
43
Q

What is a DNA probe?

A

Short, single stranded length of DNA with a label attached (radioactive or florescent)

44
Q

Purpose of DNA probes

A

To identify particular alleles of genes

45
Q

What is the purpose of primers ?

A

Provide starting sequences for DNA polymerase to begin copying
Prevents two separate strands for rejoining

46
Q

What is DNA hybridisation?

A

The binding of a section of DNA or RNA with a single stranded section of DNA (usually a DNA probe) with complimentary bases

47
Q

Effects of methylation on gene expression

A

Prevents binding of transcription factors
Prevents RNA polymerase from binging
Prevents mRNA from being made
No translation occurs

A2 Biology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions