Molecular Genetics Flashcards
how many chromosomes in a eukaryote?
46 (23 pairs)
what are autosomes?
the 1st 22 pairs of chromosomes
What are sex chromosomes?
the 23rd pair of chromosomes
what are alleles?
different forms of one gene
what are allotypes?
different forms of one protein (isoforms)
what is polymorphic?
alternative forms of one gene (many alleles)
what is oligomorphic?
few forms of one gene (few alleles)
what is monomorphic?
no polymorphism
what is homozygous?
same allele on both inherited chromosomes
what is heterozygous?
different allele on both inherited chromosome
what type of cells divide in a) mitosis b) meiosis?
mitosis: division of somatic cells
meiosis: division of germline cells
what three codons are stop codons?
TAG, TGA, TAA
what is a mutation?
an alteration or change in the genetic material
three things that can cause mutation?
- inherited
- error in DNA replication/repair
- exposure to mutagenic agents
classes of genetic diseases?
- chromosomal
- monogenic - one gene
- multifactorial - genetic and environmental factors
- polygenic - many genes
- somatic - mutation in somatic cells
- mitochondrial - mutation in mitochondrial genome
what causes single gene disorders?
a change in one or both copies of a particular pair of genes
what are the three common types of single gene disorders?
- autosomal dominantv(expressed if at least one chromosome affected i.e. heterozygous)
- autosomal recessive (expressed if both chromosomes affected i.e. homozygous)
- X-linked (only on X chromosome so females affected but males only affected if they inherit mutant gene)
Explain what it means for males and females if the X-linked disorder is recessive and if its dominant?
recessive:
for males they’ll have the disorder but can’t pass it on to male kids, only female kids.
for females, only have the disorder if mother gives them the recessive allele also.
Dominant:
fatal for both males and females
where does one inherit their mitochondrial DNA from?
the egg
what are numerical chromosome abnormalities?
the gain or loss of complete chromosomes
what are chromosome aberrations?
- deletion (section missing)
- translocation (section shifts from one chromosome to the other)
- inversion (section snipped off then reinserted the wrong way round)
what type of gene therapy is currently available to humans?
somatic gene therapy
what are three theoretical types of gene therapy?
- replacement (of mutant gene with correct one)
- correction (mutated area corrected and remainder left unaffected)
- augmentation (foreign genetic material into cell to compensate for defective product of mutant gene)-this is the only gene therapy available atm
