genetic information (RNA and protein synthesis)

Question 1

what does mRNA stand for?

Answer 1

messenger RNA

Question 2

when is mRNA made?

Answer 2

during transcription

Question 3

what does mRNA do?

Answer 3

carries the genetic code from the DNA to the ribosomes, where it makes a protein in translation

Question 4

what is a group of 3 bases called in mRNA?

Answer 4

codons

Question 5

what does tRNA stand for?

Answer 5

transfer RNA

Question 6

what does tRNA do?

Answer 6

used in translation

carries the amino acids to the ribosomes

Question 7

what is the structure of tRNA?

Answer 7

single polynucleotide 
clover shape 
hydrogen bonds between base pairs 
anticodon 
amino acid binding site

Question 8

what is a sequence of 3 bases called in a tRNA molecule?

Answer 8

anticodon

Question 9

what are the stages of transcription?

Answer 9

DNA helix unwinds to expose bases and act as a template
chain of DNA acts as a template
catalysed by DNA helicase
which breaks hydrogen bonds between bases
free mRNA nucletoides in the nucleus align with exposed complementary bases
RNA polymerase bonds RNA nulceotides by phosphodiester bonds
pre mRNA spliced to form mRNA
mRNA moves out of the nuclear pore and attaches to a ribosome in the cytoplasm

Question 10

what are the stages of translation?

Answer 10

mRNA attaches to a ribosome at the start codon
tRNA has an anticodon complementary to the mRNA codon
tRNA brings along a specific amino acid
amino acids joined by peptide bonds using ATP
tRNA released
ribosome moves along mRNA to form a polypeptide
detaches at the stop codon
enters the golgi for folding and modification

Question 11

what is genetic diversity?

Answer 11

the number of different alleles of genes in a species/population

Question 12

what is genetic diversity in a population increased by?

Answer 12

mutations in the DNA

different alleles being introduced to a population after migration (gene flow)

Question 13

what is a genetic bottleneck?

Answer 13

event that causes a big reduction in a population

Question 14

why does a genetic bottleneck reduce genetic diversity?

Answer 14

reduces the number of alleles in the gene pool, survivors reproduce and a larger population is created from fewer individuals

Question 15

what is the founder effect?

Answer 15

type of genetic bottleneck where there is only a small number of alleles in the initial gene pool

Question 16

what is the purpose of natural selection?

Answer 16

to increase advantageous alleles within a population

Question 17

what happens during natural selection?

Answer 17

not all individuals in a population are as likely to reproduce
different alleles increase an individual’s chance of survival
greater proportion inherit the beneficial allele
more likely to survive, reproduce and pass on useful genes

Question 18

what are behavioural adaptations?

Answer 18

ways an organism acts to increase its chance of survival and reproduction
eg) play dead

Question 19

what are physiological adaptations?

Answer 19

processes inside an organisms body that increase its chance of survival
eg) hibernation

Question 20

what are anatomical adaptations?

Answer 20

structural features of an organisms body that increase its chance of survival
eg) thick blubber layer

Question 21

what is an example of directional selection?

Answer 21

antibiotic resistance

Question 22

what is an example of stablilising selection?

Answer 22

human birth weight

Question 23

what is directional selection?

Answer 23

individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce
could be in response to an environmental change

Question 24

what is stabilising selection?

Answer 24

individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
when the environment isn’t changing- reduces the range of characteristics