6- Inheritance, Variation And Evolution

Question 1

Sexual reproduction

Answer 1

• involves the joining of male and female gametes formed by meisosis
• mixing of gentic material taes place- variation
• takes more time and energy, need a mate and 2 parent cells

Question 2

Meiosis

Answer 2

• produces games
• parent cell- diploid- full set of chromosomes in pairs
• DNA replicated
• two sets of cell division
• produces 4 genetically different gametes each with a single set of chromosomes-haploid)

Question 3

Haploid

Answer 3

Only has half the number of chromosomes

One set

Question 4

Fertilisation

Answer 4

• one gamete cell each sex - egg and sperm
• fertilisation
• produces diploid zygones
• mitosis
• diploid embryo

Question 5

Genome

Answer 5

The entire genetic material for an organsim

Question 6

Human genome project

Answer 6

Sequencing the entire human genome

Question 7

Uses of the human genome project

Answer 7

• targeted medicines/treatments
• identifying/understanding cause for genetic risk factors for disease
• evolutionary relationships/migration patterns
• identifying genes

Question 8

Alleles

Answer 8

Different form of gene
2 alleles per gene
(1 from each parent)

Question 9

Dominant

Answer 9

Always expressed in phenotupe if present

Capital letters

Question 10

Reccessive

Answer 10

Only expressed in phenotype if both are present

Lower case

Question 11

Homozgous

Answer 11

Two. Alleles are identical

BB or bb

Question 12

Heterozygous

Answer 12

Two aleles whch are diff

Bb

Question 13

How to find out probability certainproperty is had

Answer 13

• write out phenotype
• write out gametes
• draw punnet squares and times out
• find out percentage

Question 14

Sex determination

Answer 14

• 1 chromsome determines this
• female XX
• males XY
• use normal genetic cross

Question 15

Genotypic ratio

Answer 15

Dominant : recessive

Question 16

Phenotypic ratio

Answer 16

Ratio of visable trait

Question 17

Structure of DNA - when discovered

Answer 17

• 1953
• james watson and francis crick at cambridge
• rosalin franklin- xrayed it

Question 18

Where is genetic material found

Answer 18

Nucleus

DNA

Question 19

DNA

Answer 19

A polymer made up of two strands forming a double helix and nucleotide monomers
Contained in structures called chromosomes

Question 20

Gene

Answer 20

A small section of DNA in a chromosome

• each gene codes for a partiicular sequence of amino acid \
  
  • to make a protein

Question 21

Nucleotide made up of

Answer 21

• base(in middle) bound with hydrogen double bond
• glucose/sugar
• two phosphate molecules

Question 22

Structure of dna

Answer 22

-double helix
-sugar phosphate backbone
-hydrogen bond between bases
-made up of 4 complementary base pairing
A+T. G+C

Question 23

Mutations

Answer 23

A spontanous/random change to the sequence of nucleotides

Question 24

How mutations affect protein- coding region

Answer 24

• a change in base may result in a change in AA
• change in AA sequence may lead to protein that has a diff structure and so changes function
  
  • eg. Shape of enzyme active site may mean not complimentary to substrate
  • or could improve the sturcture eg. Its strength

Question 25

Mutation - non-coding region

Answer 25

-mutation may switch a gene on or off making protein when needed or not

Question 26

Point mutation

Answer 26

• 1 base change

- change to 1 codon

Question 27

Insertioon/deletion

Answer 27

Changes every codon after mutation

Question 28

Polydactyly

Answer 28

• having extra finger or toe
• caused by dominant allele
• only need 1 parent to get it

Question 29

Cystic fibrosis

Answer 29

• disorder of cell membrane
• caused by lack of regulation of water and ions in an out of certain cells inc tissue in lung
• sufferes produce mucus that’s thicker than normal making it more diff to breath
• cough a lot
• diff putting on weight
  
  • affects digestive system
• tiredness- aneamia
• easier to catch infections
• recessive allele

Question 30

Asexual reproduction

Answer 30

• mitosis takes place
• 1 parent cell needed- no genetic mixing of info
  
  • genetically identical offspring
• v. Quick so many offspring can take advantage of favourable conditions
  
  • no need to find a mate
  • less energy
• when all cells genetically identical, disease affects the whole population

Question 31

Examples of organisms that ue both asezual and sexual reproduction

Answer 31

• malaria
• fungus spore
• strawberry plants
• bulb plants eg. Daffodil

Question 32

Malaria

Answer 32

• parasite reproduces sexually in mosquito

- asexually in human/animal

Question 33

Fungus spores

Answer 33

-sexually produced spores introduce variation and often produced in response to unfavourable change in environment, so spore more likely to survive change

Question 34

Strawberry plants

Answer 34

Produce runners with identical strawberry plants on them

Question 35

Bulb plants (daffodils)

Answer 35

New bulbs can form from main bulb and divide of, each new bulb can grow into a new identical plant

Question 36

Codon

Answer 36

• 3 nucleotides/bases in a sequence
• have 23 codons
  
  • 20 AA
  • 3 stop coding codons
• each codon codes for one specific AA by binding to a complementary tRNA molecule into AA attatched
• order of bases controls order in which amino acids are assembles to produce particular protein

Question 37

Transcription

Answer 37

• DNA sequence copied in a molecule of mRNA
• in nucleus
• opposite base in mRNA
• have no T so has U instead

Question 38

Translation

Answer 38

• nucleic acd to AA/poly peptide
• mRNA carries a copy of gene to a ribosome (exits nucleus to cytoplasm)
• ribosome takes in mRNA
• carrier/tRNA attatched to AA
• tRNA move to ribosome and attatches mRNA for particular use
• two AA next to each other bod-strong polypeptide change
• amino acids released into cytoplasm
• continues until reaces into cytoplasm
• continues until reaches stop codon in which polypeptide is released into cytoplam
• in cytoplasm, polypeptide folds into protein shape