INHERITANCE, VARIATION AND EVOLUTION Flashcards
DOES ASEXUAL REPRODUCTION INVOLE the fusion of gametes?
NO
what type of offspring is linked with asexual reproduction
genetically identical to the parent
how many parents are involved in asexual reproduction
1 parent
is there a lot of variation in asexual reproduction
no there is little variation
what are copies produced buy asexual reproduction called
clones
what type of cell division is used in asexual reproduction
mitosis
what does sexual reproduction involve between gametes
it involves the fusion of gametes
in sexual reproduction is there variation in the offspring if there is why
yes because there is a mixing of genetic information
what type of cell division is used in sexual reproduction
meiosis
what are the sex cells in animals
egg cell and sperm
what are the sex cells in plants
egg cells and pollen
which type of reproduction leads to variation in the offspring
sexual reproduction
advantages to sexual reproduction
produces variation in the offspring
if the environment changes variation helps them to survive through natural selection
disadvantages to sexual reproduction
mate is required
it takes time and energy to find a mate
it is slower than asexual reproduction
advantages to asexual reproduction
one parent is needed
faster than sexual reproduction
many identical offspring can be produced by mitosis when conditions are favourable
more time and energy efficient as you do not need to find a mate
disadvantages to asexual reproduction
offspring are clones so there is little variation
if environmental condtions change the offspring is affected
what does mixing of genetic information lead to
variation in the offspring
why does sexual reproduction result in variation
because the gametes from each parent fuse, So half the genetic information comes from the father and half from the mother. this mixing of genetic information leads to variation in the offspring
what type of cells are produced by meiosis
gametes
why is there little variation in offspring produced by asexual reproduction
the offspring are produced by mitosis from one parent
how do malaria parasites reproduce
they reproduce sexually in mosquitoes and asexually in their human host
how do fungi reproduce
they can reproduce asexually but can also reproduce asexually to give variation
what form of reproduction produces seeds in flowering plants
sexual
what is DNA
DNA is a polymer with two strands that are twisted in a double helix structure
what is a gene
small section of DNA
what is a genome
a genome is the entire genetic material of an organism
what does each gene code for
a particular sequence of amino acids to make a particular protein
what are the four bases attached to a sugar
A C G T
name the parts that make up a nucleotide model
phosphate sugar and base
what does a section of three bases code for
a particular amino acid
what is a mutation
is a change in the order of bases that causes the wrong protein to be made
what controls the order in which amino acids are joined together in a protein
the order of bases in the DNA
mnemonic to remember the complementary strands in DNA
TIGERS ARE GIANT CATS
T & A
C & G
what are the non coding parts of the genes involved in
involved in switching genes or parts of genes on and off
what is an allele
different forms of a gene
what is a phenotype
the type of characteristic you have
what is a genotype
what genes you have
what is meant by the term homozygote
when alleles are the same
what is meant by the term heterozygous
when the alleles are different
what chromosomes do females have
XX
what chromosomes do men have
XY
Name a genetic disorder that is caused by a dominant allele
polydactyly
name a genetic disorder that is caused by a recessive allele
cystic fibrosis
what does embryonic screening involve
it involves tests to diagnose genetic disorders before the baby is born
what can embryos be screened for
genetic disorders
what causes cystic fibrosis
it is caused by a recessive allele
what causes polydactyly
it is caused by a dominant allele
can polydactyly be inherited if just one parent carries the defective allele
yes because polydactyly is caused by a dominant allele
can cystic fibrosis be inherited if just one parent carries the defective allele
no because cystic fibrosis is caused by a recessive allele, for the child to have the disorder both parents have to have the disorder themselves
why wont someone heterozygous for the cystic fibrosis allele have the disorder
because the allele that causes cystic fibrosis is recessive, so you have to have two recessive alleles to have the disorder. Heterozygous people have one dominant and one recessive allele
arguments against embryonic screening
it is expensive
embryos are created and destroyed- ethical reasons
unreliable, false negative could lead to a baby being born with a disorder could be born and a false positive could lead to a healthy pregnancy being terminated
arguments for embryonic screening
it will help to stop people suffering
treating disorders costs the government a lot of money
gives parents a choice
explain why offspring produced by asexual reproduction are genetically identical
they only have one parent and the cells divide by mitosis
explain why two parents with cystic fibrosis can have a child without the condition
the parents are heterozygous meaning that each parent will carry the recessive gene that causes cystic fibrosis. the child could inherit the recessive gene from each parent and be homozygous recessive
compare mitosis and meiosis
mitosis includes one cell division and two daughter cells are formed, in mitosis the number of chromosomes remain the same and the resulting cells are identical to parent cell and each other
meiosis includes two cell divisions, four cells are formed, in meiosis the number of chromosomes are halved and the resulting cells are genetically different from parent cell and each other
protein synthesis in the cell
- a gene produces a template,
- the template leaves the nucleus and attaches to a ribosome
- a carrier molecule carrying an amino acid attaches to the template in a specific order
- the amino acids join and the completed protein detaches from the carrier molecules and folds into the final protein shape
dominant allele
is awlays expressed even if one copy is present
expressed a capital letter
eg the allele for brown eyes is dominant , you need only copy of this allele to have brown
recessive allele
is only if the individual has two copies and does not have the dominant allele gene
lower case
eg the allele for blue eyes is recessive, you need two copies of this allele to have blue eyes
