Module 37 Flashcards
Mutations
Mutations
Any heritable change in the nucleotide sequence of DNA
Point Mutations
change in a single nucleotide base pair
Nucleotide Substitution
change in a single nucleotide base pair
Why do most mutations have no detectable effect on an organism
Most do not occur in a gene, so it will not be transcribed and translated
b-Beta Globin
Subunit of hemoglobin that helps carry oxygen in red blood cells
Synonymous Codons or Silent mutations
Codons that specify the same amino acid, sequnece doesn’t change
What do neutral or silent mutations result in
Synonymous Codons, do not change amino acid sequence
Where do most synonymous codons differ within the identity of the nucleotide
At the third position or 3’ end
Missense mutations or nonsynonymous mutations
Nucleotide substitution that results in an amino acid replacement
Nonsense mutation
Changes the amino acid into a stop codon, shortening and producing an unstable protein.
Noncoding DNA
Doesn’t code for DNA regions , RNA, or proteins
What causes cystic fibrosis
Mutation for the transmembrane conductance regulator protein, CFTR
The protein becomes degraded before reaching the membrane and now chlorine ions can’t flow out of the cell very well
Water follows chlorine ions by osmosis, and since the ions aren’t leaving the cell, neither is the water, causing buildup in the cells
What is cystic fibrosis
The production of abnormal secretions in the lungs, liver, pancreas, and other glands
Small deletions/ insertions
Exact multiple of three nucleotides
Results in a polypeptide with either more or few amino acids
What is the CFTR protein
Chloride Channel, which acts as a transporter, pumping chloride ions OUT OF THE CELL
Delta 508 Mutation
Cause cystic fibrosis
Deletion of three nucleotides that eliminates PHENYLALANINE
The CFTR protein is degraded before it reaches the membrane channel
Frameshift Mutations
A deletion or insertion of a nucleotide in a number that is not a multiple of three
Causes a shift in the READING FRAME of translation, affecting all the following downstream codons
Causes nonfunctional proteins
Transposons or Transposable elements
Moveable DNA sequences
Transposition
When a transposable element, movable DNA, moves or jumps around the genome
The Transposon moves from one area and inserts into another
What can chromosomal mutations do
Delete or duplicate regions of chromosomes containing many genes
Change in the gene copy number effects the amount of products / proteins in the cell
What happens when chromosomal mutations affect the order of genes, such as by interchanging nonhomologous arms
Do not change the number of copies of genes
Effects chromosomal pairing and regurgitation in Meiosis
Nondisjunction
When the pair of chromosomes fails to separate during the Anaphase of cell division
One daughter cell ends up with an extra copy of the chromosome and the other results with no copies
What kind of errors can occur during mitosis and meiosis
Cells can end up with extra or missing chromosomes
Down Syndrome
Extra copy of chromosome 21
Affected people have three copies of chromosome 21
Increased gene dosage
Gene Dosage
The number of copies of a gene in a cell
What can increased gene dosage result in
Increased gene expression or protein synthesis
Autosome
Chromosomes other than sex chromosomes ( other than X and Y)
Trisomy 13 and Trisomy 18
Presence of an extra chromosome in autosomes
Increased gene dosages or chromosomes results in more gene expression of those genes from that chromosomes, resulting in bad developmental abnormalities
Klinefelter syndrome
Two X chromosomes and one Y chromosome
Male, sterile individuals
Turner syndrome
Just one X Chromosome
Females, Usually sterile
“Ploidy”
number of sets of chromosomes
What kind of “ploidy’s” are humans
diploids; we have 23 sets of chromosomes, 46 total
Polyploidy
More than two sets of chromosomes
Triploidy
Condition of having three sets of chromosomes in the genome,
What crops and what percent of crops are polyploid
wheat, potatoes, bananas, olives, sugarcane, coffee
30-80%
Genotype
Genetic makeup
Phenotype
observable characteristic
Genetic Makeup
specific DNA sequences at particular genes or the makeup across the entire genome
Down syndrome genotype
three copies of chromosome 21
the syndrome is the phenotype
Alleles
Different forms of any gene
Correspond to different DNA sequences in the genes
Homozygous
Someone who inherits THE SAME ALLELE of a gene from each parent
aa, AA
Heterozygous
Someone who inherits A DIFFERENT ALLELE of a gene from each parent
Aa
What determines if a mutation is beneficial, neutral, or harmful
What kind of DNA it affects (noncoding vs coding)
If it affects chance of survival and reproduction
Depends on the enverionment
AA allele. for B-globin
Don’t have anemia nor malaria protection
AS allele for b-globin
Mild anemia and Malaria protection, which is beneficial in environments like Africa were Malaria is widespread.
SS Allele for B-globin
Sickle-Cell Anemia
Sickle-Cell Anemia
Polymerization of the hemoglobin causes red blood cells to change from oval to crescent shape, preventing it from efficiently carrying o2
May block capillaries affecting vital organs, and tissues
Spontaneous Mutations
When mistakes escape the DNA polymerase proofreading function
Mutagens
Agents that increase the probability of mutations
Ex. smoke, chemicals, raidiation
How does horizontal gene transfer occur
Conjugation
Conjugation
Pili connects bacterial cells to each other, connecting them.
Once joined, the pili contracts and opens a pore-like opening, allowing cell to cell transfer
Transformation
Process where DNA is released by cell breakdown and taken up by other cells
Types of horizontal gene transfer
Transformation, Virus (transduction), and Conjugation
Transduction
DNA is transferred from a Donor to a recipient by a virus
