5.1 - reproduction, meiosis and genetic crosses Flashcards
asexual reproduction +
- faster than sexual
- only one parent needed
- more time/energy efficient (don’t need to find mate)
- many identical offspring produced when conditions favourable
sexual reproduction +
- produces variation in offspring
- if environment changes variation gives survival advantage by natural selection
- natural selection can be sped up in selective breeding to increase food production
mutation
random change in dna
some animals/plants can do both sexual and asexual reproduction
a - when conditions are favourable
s - if circumstances change - adapt to increase survival (variation)
onion reproduction
a - produces bulbs that can divide and grow into new plants
s- produces seeds when flowers are pollinated
fungi reproduction
a - made by mitosis and grow into genetically identical fungi
s - spores are made by meiosis
strawberry reproduction
a - plant makes runners on which new plants grow
s- pollen and ovules fuse to make a seed
malarial parasite
- mosquito feeds on human
- malarial parasite transferred to human
- it feeds grows + divides in the liver
- cells of the parasite invade red blood cells
- asexual cycle starts (triggered by food/ warm conditions)
- sexual forms of the malarial parasite are produced (believe this is triggered by the immune system challenging it)
- sexual forms are transferred to the mosquito
- sexual reproduction of the malarial parasite in the mosquito
chromosome, dna , gene, genome - size order
- DNA - polymer of nucleotides
- gene - instructions for a characteristic
- chromosome- 46
- genome - entire genetic material of a cell/organism
mitosis use
- produces 2 genetically identical offspring
- for growth and repair
meiosis use
cell division - produces 4 genetically diff. cells for variation
gametes
sex cells
- single set of chromosome
zygote
cells formed by fusion of 2 gametes
male chromosomes
XY
female chromosomes
XX
meiosis
- parent cell - 46 chromosomes
- chromosomes copy themselves
- chromosomes pair up (homologous chromosomes pair up - 1from mum with 1 from dad)
- sections of dna are swapped within each pair of chromosomes
- chromosome pairs sepearated and the cell divides (one member of each pair in each new cell)
- original and copied chromosomes are separated from each other + cells divide in 2
- 4 genetically different gametes are made - 23 chromosomes
haploid
cells with a single chromosome from each pair
diploid
cells with a pair of each chromosome - 1 from mum 1 from dad
chromosome
thread like structures of DNA in the nucleus
gene
a section of DNA containing instructions for a characteristic
allele
an alternative form of a gene eg blue allele of eye colour
genotype
the alleles present for a particular gene eg Bb for eye colour
phenotype
the characteristic that is show eg brown for eye colour
dominante allele
allele that’s always expressed even if another allele is present - CAPITAL
recessive allele
2 copies of allele must be present to be expressed - lowercase
homozygous
a person with 2 of the same allele for a characteristic
heterozygous
a person with 2 diff allele for a characteristic
cystic fibrosis
- thick mucus
- 7th pair of chromosomes
- recessive - have to have 2 to suffer from it but can have one and be a carrier
generic diagram rules
- show parents phenotypes
- show parents genotypes
- DOMINANT recessive
- pure gametes in circles
- show all combinations of alleles
- pure an x to show the cross
