variation/inheritance Flashcards
what chemical makes all genetic material in a cell
dna-deoxyribonucleuic acid
what does dna contain
coded info to put organism together and work
what do the contents of dna determine
your inherited characteristics
how is dna found in plants and animals
nucleus as long pairs of chromosomes
how is dna a polymer
it is made of 2 strands coiled to form a double helix
what is a gene
small section of dna found on chromosomes
what does code for mean
tells cell to make
how is a specific protein made
gene codes for particular sequence of monomers(amino acids)
how many amino acids are there to be used in coding but what still happens
20
-make up 1000s of unique proteins
what is the role of genes
order to put amino acids together
what are egs of proteins a cell can produce
haemoglobin or keratin
what are egs of cells dna can make
rbc
skin cells
what is the genome
whole genetic material in an organism
What does understanding the human genome allow
2 facts
-scientists to identify genes linked to diseases
-genes linked to inherited diseases and learning abt them to develop treatment
What does understanding the human genome allow
3rd fact
tracing of migration by differences of genome
what repeating units make up dna strands
nucleotides
what does each nucleotide contain
a sugar,base and phosphate group
what groups form the backbone of the dna strands
A sugar and phosphate group
what are the 4 bases
a
c
t
g
what do the bases join to
1 of 4 joins to each sugar
What is complementary base pairing
a pairs with t
c pairs with g
each base of a pair is on opposite strands of the helix
what do the order of bases in a gene determine
order of amino acids in a proteins
what codes for each amino acid
sequence of 3 bases
What do parts of Dna that dont code for proteins do
switch gene on and off to show whether it is
expressed or not(to make a protein)
where are proteins made
in ribosomes
what does mRNA do
carries code from dna to ribosome
how is mRNA made
copying code from dna to make proteins
eg of proteins and functions
enzymes
hormones-carry messages around the body
after chain of amino acids is formed what does it do to carry out its function
folds into a unique shape
what is a mutation
random change in an organisms dna that may/not be inherited
what increases chance of mutation
radiation exposure
what do mutations cause in dna
change in sequence of bases in gene which forms a genetic variant and protein variant
some mutations are harmless
list egs of harmful mutations
enzyme active site
structural proteins(eg collagen) may lose strength
what can change how genes are expressed
mutation in non coding Dna
what are types of mutations
insertions
deletions
substitions
What does insertion do
adds base into dna sequence where it shouldnt be affecting amino acids they code for(can be many)
which mutation types have knockon effects
-deletion and insertions
what is sexual reproduction
genetic information from 2 parent organisms combine to produce genetically different offspring
what do mother and father produce in reproduction
gametes
what is the fusion of egg and sperm and what is the cell it makes called
fertilisation
-diploid
how is there variation in a fertilised egg
gametes fuse and because there are 2 parents offspring have mix of parents genes/chromosomes
what happens in asexual reproduction
1 parent produces genetically identical offspring by mitosis
what is the new cell by asexual reproduction called
clone
what is a clone
genetically identical copy off a parent
what makes the sexual reproduction of a flowering plant different to animals
their sperm is pollen
what organisms do asexual reproduction
bacteria
some plants/animals
how are gametes produced
cells dividing by meiosis
where does meiosis happen in humans
reproductive organs
ovaries in woman
testes in males
1st step of meiosis
cell duplicates genetic info (chromosomes)
which arrange themselves in pairs
2nd step of meiosis after chromo replicate
pairs of chromosomes line up in centre of the cell
3rd step of meiosis after chromosomes align
pairs are pulled apart so each cell has one copy of each(mix of fathers and mothers
cell divides
4th step of meiosis after chromosomes pulled apart
chromosomes realign in centre of each cell where arms are pulled apart
why are all the gametes from meiosis genetically different
all the chromosomes get shuffled and each gamete gets a random 23
what are you left with after meiosis
4 genetically different gametes with 23 chromosomes
what happens after gamete fusion
new diploid cell divides by mitosis to produce copies of itself
how are lots of cells produced in an embyro
repeated mitosis by the fertilised egg cell
what happens as an embyro develops
cells begin to differentiate to specialised cells that make up an organism
1 advantage of sexual reproduction
variation in offspring
2nd advantage of sexual reproduction
variation increases offspring’s survival chance in a change of environment
3rd advantage of sexual reproduction
better adapted individuals will survive and are more likely to pass characteristic on
(natural selection)
how can we speed up natural selection
which is a plus of sexual reproduction
by selective breeding
what is selective breeding
individuals with desired characteristics bred to produce offspring with these
what is an example of selective breeding
increasing food production by breeding animals that produce a lot of meat
1 advantages of asexual reproduction
only 1 parent needed
2nd/3rd advantage of asexual
less energy used as organisms dont have to find a mate
faster
4th advantage of asexual
many identical offspring can be produced in favourable conditions
what is an eg of favourable condition
bacteria in human body
what is a con of asexual
if there is an unfavourable change in the environment that kills one organism they could all die as they are genetically identical
