reproduction + genetics

Created by

Martha Nutt

Cards (41)

define sexual reproduction
involving the fusing of gametes. there will be 2 parents
define asexual reproduction
doesn't involve gametes . only 1 parent
where does meiosis occur in females?
ovaries, to produce ova (gamete)
where does meoisis occur in males?
testes, to produce sperm (gametes)
how many chromosones do most human cells contain?
46 chromosones, found as 23 pairs
how many chromosomes do red blood cells have?
0
how many chromosomes do gametes have?
23
why is there genetic variation in gametes
gametes contain random mixtures of original chromosones, so introduces variation
how many daughter cells are formed in meoisis?
4 daughter cells
how many daughter cells are produced for mitosis?
2
where do both mitosis and meoisis occur?
in nucleus of cell
what are nucleotides?
repeating units of DNA
what do genes code for?
proteins
what are the 4 complementary bases in DNA?
A always pairs with T
C always pairs with G
what type of polymer is DNA?
a polynucleotide
what is the structure of dna?
double helix
describe the structure of DNA
2 strands twisted to form a double helix structure
run in opposite directions, held together by weak intermolecular forces
what is mRNA
an opposite, complementary copy of the DNA, which is used to determine the particular sequence of amino acids to make a specific protein
what are genes
codes of inheritance. small sections of DNA each of which determines an inherited characteristic
define genome
the entire genetic material of the organism
define genotype
combination of the alleles
define phenotype
the characteristic
define homozygous
both copies of the gene are the same allele
define homozygous recessive
two recessive alleles
define homozygous dominant
two dominant alleles
define heterozygous
when two copies of the gene are different alleles
define carrier
when a person inherits one recessive allele but this characteristic is not expressed
what is an advantage of embryo screening?
allows parents to make an informed decision about termination
what are the disadvantages of embryo screening?
procedure could cause a miscarriage
false positive - parents could terminate unnecessarily
false negative - parents won't make informed decision
test is expensive
describe amniocentesis
carried out at 15/16 weeks of pregnancy
involves taking some of the fluid from around the developing foetus using a needle. which contains fetal cells that can then be used for genetic screening
describe chorionic villus testing
10/12 weeks pregnancy
taking a small sample of tissue from the developing placenta, ( using a catheter for transcervical method or a needle for transabdominal method ) which can then provide fetal cells to screen
what alternative genetic testing methods can be used other than embryo screening?
analysing fetal cells found in blood of mother
embryos produced by IVF to be tested before they are implanted in the mother (so that only babies without the genetic disorder are born)
define haploid
A sex cell (gamete) that contains one set of chromosomes.
define diploid
A cell that contains two sets of chromosomes.
how are mitosis and meiosis different?
mitosis is a form of cell division which produces two identical, diploid body cells
meiosis is a form of cell division which produces four non-identical, haploid sex cells or gametes (sperm and ova in humans)
describe stage 1 of mitosis
DNA replicates to form 2 copies of each chromosome
cell grows
increase number of subcellular organelles eg mitochondria
describe stage 2 mitosis
mitosis occurs
one set of each chromosome is pulled to each end of cell
nucleus divides
describe stage 3 of mitosis
cytoplasm and cell membrane divide to form 2 genetically identical cells
what do chromosomes contain?
lots of genes, which determine genetic features
how many pairs of chromosomes do human body cells contain
23 pairs
gametes have single chromosomes