MODULE 6:GENETIC CHANGE Flashcards
Define a mutagen
an agent such as electromagnetic radiation or chemicals that can cause genetic mutation
Define mutation
a permanent change in the nucleotide sequence of an organism’s genome
Give the Effect of electromagnetic radiation, how they operate
Cause:X-Rays and Gamma Rays
Effect: classed as ionising radiation because when they strike an atom/mlcle they, ‘bump off’ an eletron leaving an ion
What is the outcome of ionising radiation
It can break DNA molecules
Damage bases and cause chromosomal deletion
It also causes cross-linking of DNA to itself and proteins
Give the Effect of electromagnetic radiation, how they operate
Cause:UV light
Effect: short wavelength and high energy ways are absorbed by DNA
Which excite adjacent prymidine (C and T) to form covalent bonds
Outcome of UV light exposure
pyrimidine dimers to form possible translation and transcription errors
Give the Effect of chemicals and how they operate
Cause: Nitrogen mustard
Effect: alkylating agents produce mutations by adding small hydrocarbon groups to either bases or backbone of DNA
Outcome of : Nitrogen mustard
Possible source
Bone marrow suppression === anemia
Side effects of chemotherapy
Give the Effect of chemicals and how they operate
Cause: dimethyl nitrosamine
removes amine groups from bases such as converting C bases to U and producing mutations
Outcome of dimethyl nitrosamine
Possible source
Lung Cancer
Source: produced in the stomach of animals after eating foods containing nitrous acid
Give the Effect of chemicals and how they operate
Cause: proflavin
Insert themselves into DNA stretching it and causing frameshift mutations
Outcome of Proflavin
Possible source
Tumors
used labs as dyes
Define frameshift mutations
mutations that result the way we read codons in mRNA
Give the Effect of naturally occuring mutagens and how they operate
Cause: VIRUS HPV
HPV hits the genome, disrupting and rearranging nearby host-cell genes “This can lead to overexpression of cancer-causing genes in some cases, or it can disrupt protective tumor-suppressor genes in others. Both kinds of damage likely promote the development of cancer.”
Outcome of HPV
This can lead to overexpression of cancer-causing genes in some cases eg brca gene which can result in Cancer
Give the Effect of naturally occuring mutagens and how they operate
Cause: metals such as mercury
can induce chromosomal variation or abnormal cell divisions in animals or plant cells
Outcome of mercury
Cancer
Give the Effect of naturally occuring mutagens and how they operate
Cause: Reactive Oxygen Species (ROS)
result in mutagens attached to nitrogenous bases as well as DNA strand breaks and crosslinks
What are the different types of point mutations
Silent, nonsense and missense, frameshift insertion and deletion
Normal DNA LEVEL: TTC
mRNA LEVEL: AAG
Protein: Lys
Example DNA LEVEL: TTT mRNA: AAA protein: Lys what type of mutation is that ?
point mutation, silent mutation
Normal DNA LEVEL: TTC
mRNA LEVEL: AAG
Protein: Lys
Example DNA LEVEL: ATC mRNA: UAG protein: STOP what type of mutation is that ?
Nonsense point mutation
Normal DNA LEVEL: TTC
mRNA LEVEL: AAG
Protein: Lys
Example DNA LEVEL: TCC mRNA: AGG protein: Arg what type of mutation is that ?
Missense, point mutation
missense is equal to
changed amino acid in polypeprtide chain
When does chromosomal mutation occur
when a cell in undergoing cell division
What causes mutations
Mutagens
What are the four main types of chromosomal mutations
Deletion
Inversion
Translocation
Duplication
Explain what happens during deletion chromosomal mutation
Chromosome breaks and a section of DNA is lost
Explain what happens during inversion chromosomal mutation
The chromosomal DNA breaks free, reorients and rejoins in the reverse order
Explain what happens during translocation chromosomal mutation
section of the chromosome breaks off and rejoins the non-homologous chromosome
Explain what happens during duplication of chromosomal mutation
a section of the chromosome is copied and added
When homologous chromosomes pairs fail to segregate during cell division is called
non-disjunction
What does non-disjunction result in
aneuploidy - offspring may have an extra or missing chromosomes
What is the difference between germline and somatic mutation
Somatic - future generations are not affected
Germline- 50% of the offspring may inherit the disease
What are the effects of point mutation
New alleles are formed in germline and somatic cells
what are the effects of chromosomal mutation
Chromosomal mutations cause- abnormalities such as Trisomy 21
Cell death, malfunction and cancer in somatic
How significant are DNA mutations in the coding segments of DNA
May result in no effect or failure to produce a functional polypeptide
How significant are DNA mutations in the coding segments of DNA
May have no impact or result in changes in gene expressions eg Huntington’s Disease
Define a gene pool
A gene pool is a collection of genes within an interbreeding population at a particular time
define gene/allele frequency
How often different alleles occur in the gene pool of a population is known as the allele frequency
(number yawo haichinje)
What causes genetic variation
meiosis, fertilisation and mutation
What causes allele frequency
mutation
What increases the gene pool
meiosis
how does fertilisation cause genetic variation and what is the effect on the gene pool
allows new combinations of alleles and natural selection may play a role in selecting fit parents
how does meiosis cause genetic variation
Random segregation -causes new combinations of chromosomes and hence alleles
crossing over- new combinations along chromosomes
how does meiosis cause genetic variation
produces new alleles and changes in gene regulation and expression or chromosome number and arrangement
Random chance effects on allele frequency in gametes and populations esp if population is smallis the definition for
genetic drift
Define gene flow
movement of genes between populations because of migration == genetic variation
What is the effect of mutation on gene pool
initially mutation increases the variety of alleles in the gene pool
What is the evaluation of mutation on the gene pool
most significant change. Mutation impact can be positive, negative or neutral
What is the effect of genetic drift on a gene pool
Increases or decreases in alleles frequency by chance
Evaluate the effect of genetic drift on a gene pool
less likely to alter the gene pool
What is the effect of gene flow on gene pool
increases genetic diversity due to gene flow
Evaluation of gene flow on a gene pool
Generally positive impact by increasing the diversity of the gene pool
