Mod 6 - IQ1 Flashcards
(30 cards)
What is a mutation?
A mutation is a permamnet change that occurs in the DNA sequence
What is a mutagen?
A mutagen is any agent that causes a genetic mutation. It can be chemical, physical or biological. - Many mutagens are carcinogenic, causing genetic changes that cause cells to become cancerous.
What is mutagenesis?
Mutagenesis is a process by which the genetic information of an organism is changed, resulting in a mutation
Which waves on the Electromagnetic Spectrum can cause mutations?
From UV to Gamma Ray.
- These are high energy electromagnetic radiation waves known as Ionising Radiation as they can remove an electron from an atom or molecule.
What is the effect of ionising radiations?
Ionising radiations create ions in cell contents and can alter the way 2 strands of DNA interact, shift sections of DNA in chromosomes and cause covalent bonds to form between adjacent bases.
What type of chemicals are commonly mutagens?
Chemicals which are free radicals are commonly mutagenic (they have an odd unpaired electron which is unstable)
Sources of free radicals are alcohol, tobacco smoke, heavy metals, industrial solvents and pollution.
How will chemical mutagens affect DNA?
- Some chemicals interact with DNA to produce mutagenic compounds
- Some insert themselves into DNA, changing the shape of the molecule and some change the properties of the bases
What are some examples of chemical mutagens and how they affect DNA?
Base Analogues: similar structure to normal nitrogenous bases in DNA and can cause the wrong nucleotide to be inserted opposite to them min replication. e.g. 5-bromouracil acts like thymine.
Alkylating Agents: compounds that work by adding an alkyl group to the guanine base of a DNA molecule, preventing strands of the double helix structure from linking. e.g. Sulfur and Nitrogen mustards
Intercalating Agents: Insert themselves between the bases causing a code frame shift e.g. Proflavine and acriflavin
Wht are some naturally occuring mutagens?
Bacteria, viruses and other micro-organisms can affect the host cell as a mutagen.
- They can insert their genome or produce toxins that disrupt DNA. e.g. Human papillomavirus (HPV), or more commonly known as genital warts caruses cervical cancers.
- The aging process of cells and reproductive systems also lead to an increased amount of mistakes in DNA replication and mutation.
What are point mutations?
Point mutations are a mutation that laters adds or removes one or very few nucleotides from a sequence of DNA or RNA.
- They typically affect one gene.
- This involves substitution and framshift mutations.
What is a substitution mutation?
A substitution mutation is a point mutation where one nucleotide is replaced by another. There are three different types:
Silent Mutation: When a substitution results in a new codon that still codes for the same amino acid Missense Mutation: Results in an amino acid replacement, and still produces a protein
Nonsense Mutation: Results in the creation of a stop codon (UAA, UAG, UGA)
What is a frameshift mutation?
Frameshift mutations involve one or two nucleotides being either added or removed from a nucleotide sequence.
- This alters every codon in the sequence from that point onwards.
- This has significant effects on the polypeptide produced, producing a non-functional polypeptide.
What is a disease caused by Point Mutations? (CF)
Cystic Fibrosis - Cystic Fibrosis is a recessive inherited disorder most common among people of European descent.
- The most common mutation is a small frameshift mutation that reduce the activity of the CFTR protein. - This causes a thick sticky mucus to form in lungs, leading to trouble breathing, salty sweat, infertility in individuals and a shortened life span (42-50 years) Point mutations are also present depending on the severity of cystic fibrosis.
What is a disease caused by point mutation (SCA)
Sickle Cell Anemia.
- A recessive disorder caused by a single substitution in the gene that creates haemoglobin, which carries oxygen in the blood.
- Normally glutamic acid is produced in the chain, but the substitution causes valine to be produced at the spot instead.
- When people have two copies of this mutation, it results in thin sickle shaped blood cells that cannot carry oxygen properly.
- This is a prevalent disease in sub-Saharan Africa where the disease catually helps protect individuals against malaria.
- It can be treated with folic acid, blood transfusions, bone marrow transplants and certain prescription drugs.
Symptoms - Anemia - Obstruction of blood vessels - Chest Pain
What are chromosomal mutations?
Chromosomal mutations involve changes to chromosomes including: Structural Abnormalities
- Mutations within chromosomes such as chunks of cod have been deleted, duplicated or translocated. Numerical Abnormalities
- When an individual has abnormal number of chromosomes (22 somatic, 1 sex chromosome)
What are structural abnormality mutations?
Structural abnormality mutations affect large sections of a chromosome, typically multiple genes. These mutations generally occur during meiosis OR by mutagens.
5 main types:
Duplication - Involves the replication of a section of a chromosome that results in multiple copies of the same genes on that chromosome.
Inversion - Involves a section of the sequence breaking off the chromosome, rating 180 degrees and reattaching to the same chromosome
Deletion - Removes section of a chromosome (v bad, kinda fatal)
Insertion - When a section of one chromosome breaks off and attaches to a different chromosome. This can result in some gametes with two copies of genes in the inserted section, while other gametes may be missing genes.
Translocation - A whole chromosome or segment of a chromosome becomes attached to or exchanged with another chromosome or segment.
What is a disease caused by a structural abnormality mutation?
Huntingtons disease is an inherited progressive monogenic disease that affects the nervous system causing brain degeneration with loss of control of body functions and deterioration of memory and judgement.
- This increases anxiety, depression and dementia.
- It occurs when there are more then 35 CAG repeats on the gene coding for the protein HTT
What is a Numerical Abnormality mutation?
Numerical Chromosomal abnormalities result from nondisjunction.
- This is an error in cell division where there is a failure of a chromosomal pair of 2 chromatids to disjoin during mitosis or meiosis causing a chromosomal pair of chromatids to pass to one daughter cell, and the other daughter cell receiving neither.
3 Types:
Polyploidy: The possession of more then 2 sets of chromosomes
Monoploidy: The loss of an entire set of chromosomes
Aneupoloidy: The addition of all or part of a chromosome. (caused by non-disjunction
What are somatic cell mutations?
Somatic cell mutations occur in body cells.
- These affect an individual and cannot be inherited by offspring and passed to future generations.
What are germ cell mutations?
Germ cell mutations occur in a gonad cell in reproductive organs e.g. Testes or Ova.
- This change can be inherited and passed to future generations
What are non-coding DNA segments?
Non-coding DNA are sections of DNA that aren’t expressed or translated into a proton. These are the introns in eukaryotic DNA
- These DNA segments control the action of regulatory proteins
- Thus changes in non-coding DNAs will result in a protein to be expressed at the wrong time.
How do mutations effect non-coding DNA segments?
Mutations hamper the ability of non-coding DNA to regulate gene activity. e.g. Hampering the promoters, insulaters and silencers.
- This has been associated with several types of cancer.
- Mutations in non-coding DNA can also induce various mutations in coding regions of DNA.
What are coding DNA segments?
Coding DNA is sections of DNA that are transcribed and translated to make a protein in gene expression.
- Coding DNA is the exons of eukaryotic DNA
Coding DNA segments play a vitol role in the production of proteins that control the function of numerous biological processes in our system.
What is the effect of mutations in coding regions of DNA?
Mutations in coding segments will cause mishaps in major biological processes of a system.
- This causes a number of genetic diseases.
- This can cause proteins to deviate from normal functioning to cause structural modifications.
- Some proteins can be a benefit, and increase the adaptability of an organism in changing environmental conditions.
