inheritance Flashcards
what are gametes and where are they made
sperm or egg cells
made in meiosis
what does the sexual reproduction involve
fertilisation (the fusion of male and female gametes)
there is mixing of genetic information so the offspring receives genetic information from both male and female parents
this means that we can see variation in the offspring as every gamete is different
what does asexual reproduction involve
there is only one parent so this does not involve gametes - no mixing of genetic information
this means that offspring are all genetically identical called clones
what does asexual reproduction use to reproduce instead of meiosis as asex does not involve gametes
only involves mitosis
in gametes the chromosomes are…
not paired, they are single
a human gamete contains 23 single chromosomes
where does meiosis take place
reproductive organs
testes or ovaries
stage one of meiosis
all of the chromosomes are copied
the cell now divides into two
now both of these cells divide again forming the gametes
their 23 chromosomes are single, not paired
each of the four gametes produced are genetically different from each other
where is DNA found and what does it do
chromosomes - they contain DNA
determines our inherited features
what does DNA contain
two strands wrapped around each other to form a double helix
what is a gene
a small section of DNA on a chromosome
how are protiens made
by joining together amino acids
what does each gene encode for
a specific sequence of amino acids to make a specific protein
what is the genome
the entire genetic material of an organism
3things that understanding the human genome helps with
- to search for genes that are linked to a disease e.g genes that increase the risk of developing cancer
- help us to understand and treat inherited disorders e.g cystic fibrosis
- trace migration patterns from the past - helping people to discover their ancestry
what are alleles
versions of a gene
what does the genotype of a person tell us
the alleles present
ex of homozygous
EE- homozygous dominant
ee - homozygous recessive
what does the phenotype of a person tell us
the characteristics caused by the persons alleles’s
a recessive allele will only be expressed if the allele
is homozygous ee, so it is not expressed if their is a dominant allele ( Ee)
what is cystic fibrosis
a disorder of cell membranes
cystic fibrosis is controlled by a
single gene, which has two alleles,
in order to have cystic fibrosis
the person has to have two copies of the defective allele - so. they must inherit a defective alelle from both of their parents
punnet square results are
only probabilities and estimates so are not 1oo percent accurate
