Genetics Flashcards
Describe the first division in meiosis
Reduction division
Homologous chrs pair up forming bivalents
Nuclear envelope breaks down
Nucleolus disappears
Crossing over of inner non sister chromatids at chiasmata
Bivalents form a double line at the equator
Spindle fibers form and attached to centromeres
Spindle fibers shorten and pull homologous chrs apart to opposite poles
Nuclear envelope reforms
Cytokinesis
Describe how crossing over and independent assortment can lead to genetic variation
Homologous chrs line up at equator in metaphase 1 independent on one another
Pulled towards opposite poles randomly resulting in gametes
Crossing over us when inner non sister chromatids form chiasmata by exchanging genetic material
Linkage groups broken
New combination of alleles
Occurs during meiosis 1
Outline the behavior of chromosomes during meiosis
▪️in prophase 1
▪️condensation of chrs
▪️bivalents form
▪️crossing over between inner non sister chromatids forming chiasmata
▪️in metaphase 1
▪️bivalents line up at equator
▪️of spindle
▪️by centromeres
▪️in anaphase 1: ▪️chrs move to poles ▪️homologous chrs separate ▪️pulled by microtubules ▪️reduction division
▪️metaphase 2:
▪️chromosomes line up at equator
▪️of spindle
▪️Anaphase 2: ▪️centromeres divide ▪️chromatids move to opposite poles ▪️pulled by mircrotubules ▪️haploid number
what is the difference in gametogensis in pollen and sperm
in pollen:no cytokinesis resulting in cells that contain 2 haploid nuclei
first haploid cells the diploid
in sperm:mitosis then meiosis
more gametes made
in sperm duct
discuss how gene mutation can occur
change in base seq in DNA during DNA replication can be substitution,deletion,addition frame shift new allele random mutagens ionising radiation UV radiation
discuss albinism
dark pigment melanin missing from eyes,skin and hair red pupils,blue pale skin and hair poor vision mutation in tryosinase enzyme is an oxidase 2CO atoms binding site for O2 transmembrane prt inactive in melanocytes tryosine cant be converted to DOPA and dopaquinone
whats an inducable enzyme
synthesis of enzyme will only occur when substrate is present
what is the diff between regulatory and structural genes
structural: genes that code for proteins req by the cell
regulatory: genes that code for proteins that regulate the expression of other genes
lac operon
promoter operator lac z lac y lac a
where RNA b-galactosidase permease transacetylase
polymerase binds lactose to glucose inc intake of
and galactose lactose
Outline the effects of mutant alleles om the phenotype in Huntington’s disease
▪️mutation of chromosome 4 ▪️dominant ▪️normal recessive allele has 10-15 CAG repeats ▪️HD has more CAG repeats ▪️larger number means early onset ▪️usual onset in middle age ▪️mis folded protein ▪️neurological condition ▪️motor control inhibited ▪️mood changes
What is the definition of linakge
The presence of 2 genes on the chromosome so that they tend to be inherited together and do not assort independently
