BIOLOGY - INHERITENCE

what are the chromosomes in the 23rd pair known as

the sex chromosomes

why type of chromosomes do men and women have

women = xx

men = xy

what does genome mean

the entire set of genetic material in an organism

what can understanding different people genomes help us find

we can track the migration patterns of our ancestors

we can identify genes which link to certain diseases

what are alleles

different versions of the same gene

what is a genotype

the entire collection of alleles we have

what is a phenotype

the characteristics you get from the genotype

how many copies does a human have of each gene

2

when someone’s alleles are both the same what are they known as referring to that gene

homozygous

what can alleles be

dominant or recessive

what is a nucleotide made up from

phosphate

sugar

base

how many types of bases are there

4

name all the four bases

A

T

C

G

what letters always have to pair up with each other

A and T

C and G

what is this known as

complementary base pairing

what is each group of three bases called and what do they do

a triplet - they code fro specific amino acids

what are the monomers of DNA called

nucleotides

what is transcription

the copying of a single gene of DNA to mRNA

where does transcription take place

nucleus

why does a gene have to be copied to mRNA

because its too big to leave the nucleus

how is mRNA different to DNA

its shorter than DNA

its only single stranded

when the mRNA leaves the nucleus and enters the cytoplasm where does it move into

the ribosomes

what is translation

the copying of amino acids to form a polypeptide

how many bases are needed to code for one amino acid

3

what is a mutation

a change in the DNA base sequence

what are the two ways organisms re produce

sexual

asexual

what type can plants do

both - asexual and sexual

what type do animals usually do

sexual

what type do bacteria usually do

asexual

what are the gametes in animals

sperm and eggs

what are the gametes in plants

pollen and eggs

how much genetic material do gametes have

half the genetic material of a normal cell

what is sexual reproduction

the fusion of male and female gametes

what is asexual reproduction

reproduction only carried out by 1 parent and involves no gametes

what does asexual reproduction mean for the offspring

there’s no genetic variation so they’re identical clones

how is asexual reproduction achieved in eukaryotic cells

via mitosis

how is asexual reproduction achieved in prokaryotic cells

via binary fission

what process is used to create gametes

meiosis

what are the examples of haploid cells

sperm and egg

what does this mean

they each only have 23 chromosomes

when a sperm fertilises the egg what type of cell do they become

a diploid cell which has 46 chromosomes

what are the main benefits of asexual reproduction

process is quick

only requires 1 parent

less energy required

what are the main downsides to asexual reproduction

no genetic variation so offspring can be susceptible to new diseases

low chances of adapting to new conditions

what is the main benefit of sexual reproduction

offspring is genetically unique/different which can lead to evolution

what are the main downsides to sexual reproduction

requires lots of energy and time due to finding a partner to mate with

during meiosis how many cells are produced

4

how many division take place

2