6.2-endless genetic crosses (inheritance) Flashcards
what do mutagens do?
increase rate of mutation
when may chromosome mutations occur?
meiosis
what are the types of chromosome mutation?
deletion inversion translocation duplication non-disjunction
what happens to chromosomes during deletion?
part of a chromosome is lost (duh)
what happens to chromosomes during inversion?
section of chromosome breaks off, turns 180 degrees, joins again
why is inversion a problem even though all genes are still present?
some genes may be too far away from their regulatory sequences to be expressed.
what happens to chromosomes during translocation?
piece of chromosome breaks off and becomes attached to another chromosome.
what happens to chromosomes during duplication?
piece of chromosome mAy bE dUpLicAtEd.
what happens to chromosomes during non-disjunction?
1 pair of chromosomes or chromatids fails to separate, leaving a gamete w an extra chromosome.
what is a condition caused by non-disjunction?
downs syndrome-extra chromosome 21
what is aneuploidy?
when the chromosome number isn’t an exact multiple of the haploid number for that organism.
what is polyploidy?
when you have more than 2 sets of chromosomes.
what’s the result of a diploid gamete and haploid gamete fusing?
triploid zygote
what’s the result of 2 diploid gametes fusing?
tetraploid zygote
during meiosis what may genetic variation result from?
allele shuffling-prophase 1
independent assortment: metaphase 1 and 2
what are 2 examples of variations caused solely by the environment?
speaking dialect
scar
what happens to chlorotic plants?
have genotype for making chlorophyll but environment preventing expression.
what is another word for homozygous?
true-breeding
what does monogenic mean?
determined by a single gene.
what does dihybrid mean?
involving 2 gene loci.
what is a gene locus?
a fixed position on a chromosome
what is codominance?
where both alleles present in the genotype of a heterozygous individual contribute to the individual’s phenotype.
what happens when a gene is said to have multiple alleles?
3 or more alleles at a particular gene locus are known.
what are autosomes?
chromosomes that aren’t sex chromosomes
the X and Y chromosomes are not fully…
homologous
why does a small part of the X and Y match?
so they can pair of before meiosis
what are examples of sex-linked characteristics in humans?
haemophilia A
colour blindness
what are the symptoms of haemophilia A?
can’t clot blood fast enough-injuries may cause bleeding or internal haemorrhage
in every female cell nucleus how many X chromosomes are active?
only 1-the other one in inactivated so females don’t have double the no of X-linked genes being expressed as males.
what happens during autosomal linkage?
gene loci present on the same autosome are often inherited together.
