Brainscape's Knowledge GenomeTM

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


See full index

A-Level Biology > 8A - Mutations and Gene Expression > Flashcards

8A - Mutations and Gene Expression Flashcards

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

Mutation

A
  • any change to the nucleotide sequence of DNA or chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mutagenic agent

A
  • any factors which increase the likelihood of mutations e.g. radiation, chemicals and some viruses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Substitution

A
  • a mutation in which one or more bases are swapped for another
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Deletion

A
  • a mutation in which one or more bases are removed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Addition

A
  • a mutation in which one or more bases are added
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Duplication

A
  • a mutation in which one or more bases are repeated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Translocation

A
  • a mutation in which a sequences of bases is moved from one location on the genome to another
  • could be on the same chromosome or different chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Frameshift mutation

A
  • Mutations that change the number of bases in the DNA code, meaning the triplet code is ‘read’ in a different way
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Mutations and amino acids

A
  • Mutations can sometimes code for the same amino acids(e.g. substitution) due to the degenerate nature of the triplet code, however others such as addition or deletion cause different amino acids to be coded for
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Mutations and proteins

A
  • If mutation changes the amino acid coded for, this will alter the primary structure, and consequently the ‘folding’ which occurs in forming the secondary and tertiary structure
  • changes the location of bonds between the amino acids and can change the shape, producing a ‘non functional’ protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Impact of mutagenic agents

A
  • Acting as a base, altering bases, changing the structure of DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Acting as a base

A
  • Some mutagenic agents are able to substitute for a base, changing the DNA sequence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Altering bases

A
  • Some mutagenic agents can alter or delete bases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Changing structure of DNA

A
  • Some mutagenic agents can change the structure of DNA, causing problems during replication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Acquired mutations

A
  • Mutations that occur in individual cells after fertilisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Tumour

A
  • A mass of abnormal cells, brought on by a mutation causing uncontrolled cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Cancers

A
  • Tumours that invade and destroy surrounding tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Tumour suppressor genes

A
  • Code for a protein which stops cells dividing or causes them to self-destruct(apoptosis), regulating the rate of cellular division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Mutated tumour suppressor genes

A
  • Mutations prevent the coding of the TSG. The protein is not coded for and cellular division is not regulated. The rate of division increases and tumours form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Proto-oncogenes

A
  • Stimulate cell division by producing proteins that make cells divide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Oncogenes

A
  • Mutated proto-oncogenes, causing the protein to be coded for multiple times, hence rapidly increasing the rate of division and forming tumours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Malignant tumours

A
  • cancers which grow rapidly, invade, and destroy surrounding body tissue
  • cells can break off and metastasise to elsewhere in the body using the bloodstream of lymphatic system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Benign tumours

A
  • Non cancerous tumours which grow slowly and are surrounded by fibrous tissue, meaning they do not metastasise
  • often harmless but can become dangerous and cause blockages or place pressure on organs
24
Q

Tumour cells

A
  • Are larger, distorted in shape with a large and dark nucleus(sometimes multiple)
  • do not have antigens, do not respond to growth-regulating processes and divide by mitosis more often than normal cells
25
Q

Causes of tumour growth

A
  • Abnormal methylation

- oestrogen

26
Q

Methylation

A
  • addition of a methyl group CH3 to a molecule. Methylation regulates transcription and translation of DNA
27
Q

Hypomethylation of proto-oncogenes

A
  • When too few methyl groups are added to proto-oncogenes, the proteins will be coded for more frequently
  • means cellular division is overstimulated, allowing tumours to form
28
Q

Hypermethylation of tumour suppressor genes

A
  • When too many methyl groups are added to tumour suppressor genes, the proteins will not be coded for
  • means cellular division goes unregulated and allows tumours to form
29
Q

Oestrogen and breast cancer

A
  • Oestrogen can stimulate cellular division, causing more naturally-occurring mutations
  • also aids the speed of replication of cancerous cells due to its stimulating effect
  • some research suggests it is able to introduce mutations directly into the DNA of certain breast cancer cells
30
Q

Preventing cancer

A
  • Screenings are now made possible to find genes of interest such as BRCA1
  • preventative measures such as a double mastectomies reduce the impact of genetic mutations on the likelihood of developing cancer
  • Furthermore, awareness of genes allows for more sensitive tests to be developed, leading to earlier and more accurate diagnoses
31
Q

Treating and curing cancer

A
  • As well as traditional chemotherapy(use of chemicals and drugs) as well as radiotherapy(targeted radiation to destroy tumour cells), new drugs have been implemented and gene therapy(the replacement of faulty alleles for functional copies) is being investigated in clinical trials
32
Q

Stem cells

A
  • Unspecialised cells which are able to divide and differentiate into specific cells
33
Q

Totipotent stem cells

A
  • Stem cells that can differentiate into any type of specialised cell found in the organism, including placenta cells, found in the embryo
34
Q

Pluripotent stem cells

A
  • Stem cells which are able to differentiate into nearly any type of specialised cell in the organism, excluding placenta cells, found after the first few divisions of the embryo
35
Q

Multipotent stem cells

A
  • Stem cells which are able to differentiate into a few different types of specialised cell, found in matured adults
36
Q

Unipotent stem cells

A
  • Stem cells which are able to differentiate into one type of specialised cell, found in matured adults
37
Q

Specialisation of stem cells

A
  • Specialisation occurs during growth as only part of the cells DNA is replicated
  • All stem cells contain the same DNA, but only some are turned on and expressed as a result of the different conditions
  • The genes that are turned on then code for proteins or other organelles that are specific to the function of the specialised cell
38
Q

Cardiomyocytes

A
  • now thought that heart muscle cells can be regenerated due to the presence of a small supply of unipotent stem cells.
  • Some researchers think this is a slow process, whereas others believe the heart could be regenerated several times in a lifetime
  • has useful application for those suffering from a heart attack or other disease
39
Q

Current stem cell therapies

A
  • Bone marrow contains stem cells which are able to specialise into any type of blood cell
  • transplants are used to insert functional stem cells into the body of an individual with a disease such as leukaemia, lymphoma or sickle-cell anaemia
40
Q

Future stem cell therapies

A
  • Stem cells could be used to replace damage nerve tissue in the spinal cord or heart tissue
  • new organs or bladders can be grown and implanted, or windpipes could be stripped and reconstructed
41
Q

Embryonic stem cells

A
  • Stem cells extracted from a 4-5 day old embryo grown using IVF which is then discarded
  • ethically controversial and faces opposition by many
42
Q

Adult stem cells

A
  • Extracted from body tissues of an adult e.g. bone marrow tissue, obtained through a simple and relatively risk-free operation.
  • less flexible, as they are multi or unipotent. Scientists are trying to find a way to increase the differential ability of adult stem cells
43
Q

Induced pluripotent stem cells (iPS cells)

A
  • Pluripotent stem cells manufactured from adult stem cells in a lab
  • transcription factors are inserted into the DNA, in an attempt to reactivate genes present in pluripotent stem cells e.g. by using a virus
  • particularly useful and less ethically controversial than embryonic stem cell harvesting, but research is needed to determine how similar they are to genuine pluripotent stem cells
44
Q

Ethical considerations of stem cells

A
  • Some object to the use of embryonic stem cells as it results in the death of a potential life, there are fewer objections to stem cells harvested from fertilised eggs, but from eggs artificially induced to divide. The impact on the life of individual who receive treatment must also be considered, as it has the potential to save and drastically improve the lives of many
45
Q

Transcription factors

A
  • Molecules which affect the rate of transcription of a gene by affecting the functioning of transcriptional machinery such as RNA polymerase or DNA helicase
46
Q

Promoter region

A
  • The region of DNA that RNA polymerase attaches to in order to begin transcription
47
Q

Activators

A
  • Bind to the promoter region, stimulating the action of RMA polymerase and increasing the rate of transcription
48
Q

Repressors

A
  • Bind to the promoter region, blocking RNA polymerase, preventing transcription of the gene
49
Q

Oestrogen as a transcription factor

A
  • Binds to oestrogen receptor within cytoplasm, forming a complex before binding to the promoter region of a gene
  • It will act as an activator or repressor depending on the cell and the environment.
  • Not all cells have oestrogen receptors so do not respond to oestrogen as a transcription factor, breast tissue cells are an example of cells which do respond
50
Q

RNAi

A
  • RNA interference. A small, double stranded molecule which prevents mRNA from target genes being transcribed into proteins
51
Q

siRNA (small interfering RNA)

A
  • In the cytoplasm, a double stranded siRNA splits and a single stranded portion of the molecule associated with several proteins and unwinds
  • siRNA binds with its complementary bases to the target mRNA molecule and cuts it into fragments
  • fragments are them moved into a processing body where they are degraded
52
Q

miRNA (micro interfering RNA)

A
  • A long, folded double strand of miRNA is cut up by enzymes in the cytoplasm
  • miRNA will associate with proteins and bind to complementary RNA
  • Due to its less complementary nature, miRNA can target different genes by binding at different points
  • miRNA physically blocks translation of the mRNA before moving it to a processing body where it is stored or degraded
53
Q

Differences between siRNA and miRNA

A
  • siRNA is a larger molecule, and more specific, miRNA is shorter but can bind to more genes as it is not as specific
  • siRNA cuts mRNA up, miRNA blocks translation, before both move the mRNA to a processing body
54
Q

Epigenetics

A
  • regulation of genetic expression based on environmental factors which do not physically alter the DNA structure, but turn on and off genes. These changes are heritable
55
Q

Inheriting epigenetic changes

A
  • Most epigenetic markers are removed from DNA between generations, but some are able to avoid this process and be passed onto offspring
  • epigenetic markers include methylation and acetylation of DNA
56
Q

Increased methylation of DNA

A
  • Methyl groups are able to bind to CpG sites, locations in the base sequence where a cytosine and guanine base are adjacent, linked by a phosphodiester bond
  • This molecule changes the DNA structure and prevents interaction with transcriptional machinery
  • means the gene cannot be transcribed
57
Q

Increased acetylation of histones

A
  • Acetyl groups bind to histone proteins, the molecules around which DNA is wrapped to form chromatin, and hence chromosomes
  • Acetyl groups create space between the histones, meaning it is less condensed
  • Transcriptional machinery is able to access acetylated histones with ease, increasing transcription of the gene

A-Level Biology (19 decks)

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