Meiosis and genetic variation Flashcards
What are gametes
the eggs and sperm
whats a zygote and whats the process called
when the eggs and sperm join together
fertilization
whats the amount of chromosomes do gametes cells have compared to body cells?
half the ammount
What is the number of chromosomes do normal body cells have?
46
What are diploid cells and how many chromies does it contain ?
that each body cell contains
two of each chromosome – one from mum and one from dad
46
What is the number of chromosomes do gametes cells have?
23
whar are haploid cells ? how many chromies does it contain ?
There’s only one copy of each
chromosome ,
23
Where does meiosis take place ?
in the sex organs to produce gametes with haploid chrome number
why meiosis requires two nuclear divisions?
2 divisions will get you from diploid to haploid
What are homologous
chromosomes
two copies of each chromosome, one of maternal origin; one of paternal origin. These maternal and paternal chromosome pairs
matched pairs containing the same genes in
identical locations along their length.
Why are Homologous chromosomes must be separated in gametes (via meiosis) prior to
reproduction?
to prevent chromosome numbers from continually doubling with each generation
when does crossing over happen ?
during prophase 1
what happens during crossover?
Basically the two chromosomes in each
homologous pair twist around each other
Wherever they ‘touch’, genetic material is
swapped between them.
At the end of crossing over the genetic
composition of each chromosome is
now different
What happens at fertilization?
a haploid sperm will fuse with a haploid egg…. which
makes a cell with the normal, diploid number of chromosomes
what is meiosis a type of ?
cell division
What does meiosis result in?
four, IDENTICAL DAUGHTER
CELLS
just like the parent cell
what are the daughter cells?
diploid
Homologous chromosomes are ?
matched pairs containing the same genes in
identical locations along their length.
when does independent assortment happen ?
happens in
metaphase I
what happens during independent assortment?
Basically, when the homologous
chromosomes line up, they do so randomly.
This means that when they are pulled apart
in anaphase, the combination of
chromosomes going into the daughter cells
is also random.
What makes humans similar?
What gives us our unique differences?
we all have the same genes
inheritance of different alleles to those genes
What happens in meiosis 1
Homologous pairs are
separated, halving the chromosome number
different from mitosis and results in genetic variation via independent assortment and crossing over
What happens in meiosis 2
same thing as mitosis
Now, sister
chromatids are separated.
What happens during interphase?
a cell
replicates it’s DNA
