Brainscape's Knowledge GenomeTM

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


See full index

Principles of tumour biology for FRCR CO1 > 1.2 The genetics of normal and malignant cells > Flashcards

1.2 The genetics of normal and malignant cells Flashcards

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

What is a nucelotide?

A

Nitrogen base + pentose (5 carbon) sugar + phosphate

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

What is DNA?

A

Nucleotide polymers formed into a double Helix

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

What are the pyramidines?

A

Cytosine
Thymine
(Uracil in RNA)

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

What are the purines?

A

Adenine
Guanine

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

How dose bases pair?

A

A = T
C =_ G

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

What is a code?

A

Sequence of bases

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

What is a codon?

A

3 mRNA bases = specific amino acid

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

What is a gene?

A

Functional piece of DNA, encodes RNA
Coposed of exons and introns

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

What are exons?

A

Bits of coding DNA

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

What are introns?

A

Bits of non-coding DNA

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

What is the promoter region?

A

TATA box

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

Where is the promoter region found?

A

5’ end

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

What is an Allele?

A

One of two versions of a gene

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

What is the genotype?

A

Genetic makeup of an organism

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

What is chromatin?

A

DNA wraps around a nucleosome which is made up of 8 histones to resemble beads on a string

Beads on a string are folded up to form chromatin which is shaped into a chromosome

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

What is a chromatid?

A

One half of a chromosome pair when the cell is in G2/M

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

What is a chromosome?

A

A structure of genetic material

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

What is a centromere?

A

Non-coding, defines the lengtht of the chromosome

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

What is a telomerer?

A

Non-coding, stops ends from fraying

Each time DNA replicates the telemeres become shorter

When they are lost the cell enters senescence and stops dividing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is aneuploidy?

A

Abnormal number of chromosomes

Caused by a lag in anaphase so the chromosome pair isn’t separated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is telomerase?

A

Reverse transcriptase enzyme that maintains the length of telomeres

Most somatic cells don’t have this enzyme and have a limited life span but stem cells, germ cells, and cancer cells express this to allow indefinite division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe transcription

A

DNA is used as a template to make mRNA in the nucleus

  1. Initiation: Transcription factor + RNA polymerase bind to promoter region and unzip double helix
  2. Elongation: RNA polymerase moves along DNA 5’ to 3’ to make mRNA
  3. Termination: polymerase and RNA strand released from template
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe translation

A

mRNA is used to make proteins

Takes place in cytoplasm/ribosome (ER)

  1. Initiation - first tRNA anticodon attaches to mRNA start codon
  2. Elongation - polypeptide bonds + amino acid chain created
  3. termination - polypeptide released by ribosome when stop codon reached
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a promoter?

A

Sequence of DNA that initiates transcription - contains TATA box

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is a response element?

A

Sequence of DNA within the promoter region that binds specific transcription factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is an enhancer?

A

Short sequence of DNA that binds proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is polymorphism?

A

variation in genes between organisms

28
Q

What are the different types of polymorphism?

A
  1. Copy number variant
  2. Single Nucleotide Polymoprhisms (SNPs)
  3. Single sequence length polymorphisms (SSLPs)
29
Q

What are Simple Nucleotide Polymorphisms?

A
  • SNPs - point mutation >1% of population
  • Single nucleotide differences, often no alteration in protein
  • Used to track inheritence of diseased genes
30
Q

What are Single Sequence Length Polymorphisms?

A

Variation in the length of repetitive DNA sequences, this is due to replication slippage during DNA replication

Micro and mini-satellites

Microsatellite:
- Repetitive DNA sequences
- Non-coding DNA
- MSI (mutator)

Minisatellite - thousands of repeats e.g. telomeres

31
Q

What is Restriction Fragment Length Polymorphisms? (RFLPs)

A

Allelle variation at site of DNA where restriction enzymes act , affecting the length of fragments produced.

Mutations e.g. point, insertion, deletion, modify the restriction enzyme recognition site.

32
Q

What is a clinical example of a point mutation?

A

Point mutation in Adenomatous Polyposis Gene in colorectal cancer

33
Q

What is a clinical example of a translocation (fusion) mutation?

A

(Exchange for one part of chrmosome for another)

BCR-ABL (T9:22) in leukaemia

34
Q

What is a clinical example of a deletion mutation?

A

(loss of all or part of a gene)

Inactivation of a tumour suppressor gene e.g. BRCA1/2

35
Q

What is a clinical example of a gene amplification mutation?

A

Multiple replications of a section of DNA that increases the number of gene copies

HER2
MET

36
Q

What is a clinical example of over-expression mutation?

A

Mutation in the promoter region of the gene leads to increased protein production

HER2

37
Q

What are some clinical examples of a driver mutation?

A

Driver mutations give a selective growth advantage to a cell by mutating genes such as oncogenes, tumour suppressor genes. Cause alterations in cell cycle control, apoptosis, DNA repair or signalling pathways.

EGFR, ALK, ROS1, KRAS, G12c

38
Q

What is epigenetics?

A

Same genome but different expression of the phenotype e.g. caterpillar and butterfly

Heritable information encoded by genome and chromatin modifications but the DNA sequence is unchanged so it is not mutations

Two types: DNA methylation and histone modification

39
Q

What is DNA methylation?

A
  • Epigenetic modification
  • Methyl group is added to a 5’ cytosine base (usually at CpG)
  • CpG islands are located in promoter regions (on 50% of genes)
  • Catalysed by DNA methyltransferases (DNMTs)
  • DNA sequence is not altered but gene expression is changed
40
Q

What does DNA methylation do?

A

Causes transcriptional silencing - switches off gene expression impedes binding of transcription factors or recruits suppressive proteins

In cancer this can lead to inactivation of tumour suppressor genes

41
Q

What is Histone modification?

A

Regulates chromatin structure and therefore gene expression

42
Q

How are histones modified?

A
  • Methylation
  • Acetylation
  • Ubiquitation
  • Phosphorylation
43
Q

What is the chromatin like in histone acetylation?

A

Relaxed with loosely packed nucleosomes

Genes can still be expressed because transcription factor can still bind

44
Q

What is chromatin like in Histone methylation?

A

Condensed with tightly packed nucleosomes

Genes not expressed because transcription factor can’t bind

45
Q

What is a proto-oncogene?

A

A normal gene that could become an oncogene if mutated, translocated or overexpressed

e.g. RAS -> KRAS, HRAS or NRAS

46
Q

What is Oncogene addiction?

A

Tumour cell depends on an single activated oncogenic pathway to maintain its proliferation and survival even though there are lots of mutations

47
Q

What is an oncogene?

A

Gene with potential to cause cancer

48
Q

What is the normal function of an oncogene?

A

Promotes cell growth and differentiation

49
Q

What affect does a mutation have on an oncogene?

A

Gain of function mutation - activates it

Can be activated by a point mutation

50
Q

What is the dominance of an oncogene?

A

Dominant - only need one mutation in an allele

51
Q

What are some examples of oncogenes?

A
  1. RAS
  2. MYC
  3. EGFR
  4. BCR-ABL
  5. BRAF
  6. MET
52
Q

What is a tumour suppressor gene?

A

Gene that protects against cancer development

53
Q

What is the normal function of a tumour suppressor gene?

A

Regulates cell growth and apoptosis

54
Q

What affect does mutation have on a tumour suppressor gene?

A

Loss of function - inactivation

55
Q

How do tumour suppressor genes lose their function?

A
  1. Loss of the gene
  2. Epigenetic silencing (e.g. methylation or histone modification)
  3. Mutation
  4. Reduced expression
56
Q

What is the dominance of tumour suppressor gene mutation?

A

Recessive - both alleles must have mutation

(both breaks fail)

57
Q

What are some examples of tumour suppressor genes?

A
  1. p53
  2. Rb
  3. APC
  4. BRCA1/2
    5.MEN1
  5. VHL
  6. NF1/2
58
Q

What is the significance of a p53 mutation?

A
  • Associated with 50% of cancers
  • Chemo and RT resistance
  • Poor prognosis
59
Q

What type of mutations affect p53?

A

Misense mutation e.g. frameshift, insertion/deletion
resulting in an altered protein

60
Q

How is genomics relevant clinically?

A

Next-generation sequencing
Define and treats molecular targets

61
Q

What is the role of p53?

A

Continually monitors for damage to DNA

Can stop the cell cycle to repair or induce apoptosis

62
Q

What activates p53?

A
  1. DNA damage
  2. Oncogene activation
  3. Aberrent growth signals
  4. Cell stress:
    - Hypoxia
63
Q

What does p53 do inside the cell?

A
  1. Cell cycle arrest or senescence
  2. Repair DNA
  3. Cause apoptosis
  4. Inhibit angiogenesis
64
Q

What is Li Fraumeni syndrome?

A

Autosomal dominant p53 mutation (note, tumour suppressor gene mutations are usually recessive)

Associated with brain, breast, adrenal, leukaemia, sarcoma

65
Q
A

Principles of tumour biology for FRCR CO1 (4 decks)

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