P2 CODOMINANCE + higher 3b genetics / inheritance

Question 1

what is a gene?

Answer 1

A gene is a small section of DNA on a chromosome that codes for a particular sequence of amino acids

Question 2

what is a genome?

Answer 2

A genome is hereditary information encoded in DNA.

Question 3

what is found in the nucleus?

Answer 3

nucleus of a cell contains chromosomes

Question 4

where are genes located?

Answer 4

in the chromosomes

Question 5

what is the structure of a DNA molecule?

Answer 5

• there are bases (which pair up), AT and CG
• these make up the shape and are the “backbone” of it
• it is a double helix structure

Question 6

what are nucleotides?

Answer 6

the basic units of DNA

Question 7

what do nucleotides consist of?

Answer 7

deoxyribose sugar, phosphate and a base

Question 8

what is an allele?

Answer 8

different versions of the same gene (like eye colour)

Question 9

what is the purpose of an allele?

Answer 9

to give differences in inherited characteristics

Question 10

what is protein synthesis?

Answer 10

the process in which cells make proteins from DNA

Question 11

how does protein synthesis work?

Answer 11

mRNA, a copy of DNA moves from the nucleus into the ribosomes. proteins are synthesised in the cytoplasm. they are then folded into a specific shape which makes a protein for a job. protein synthesis happens in two stages transcription and translation.

Question 12

what is mRNA?

Answer 12

messenger RNA

Question 13

what happens in the transcription process?

Answer 13

• DNA unwinds and the hydrogen bonds break
• exposes the gene to be transcribed
• a complimentary copy of the code from the gene is made, mRNA
• it then leaves the nucleus via a pore
• code it is read in threes

Question 14

what happens in the translation process?

Answer 14

• the mRNA attaches to a ribosome
• in the cytoplasm there are tRNA, which have a triplet of unpaired bases at one end, and an area where a amino acid can attach itself
• the tRNA molecules bind with specific amino acids and bring them to the mRNA on the ribosome
• the anticodon pairs with a codon
• this process continues until a stop codon is reached
• this is where the amino acid is complete forming a polypeptide

Question 15

what happens if there is a wrong code? (didnt read the right base in one stage)

Answer 15

Each triplet codes for one amino acid, if one letter is changed the whole structure of the protein is changed and causes defects

Question 16

what are the three types of mutations that happen when the codes are being read?

Answer 16

Substitution, not that harmful
○ Not coding the right letter, so another letter takes its place
○ Doesn’t change the triplets and only effects one protein code
Deletion, can be very harmful
○ Misses a letter, so it deletes a part of a triplet
○ Changes every triplet after that so it can be very harmful, none of the protein codes would be the same
Addition, can be very harmful
○ Opposite of deletion, has the same effect.

Question 17

what does dominant allele mean?

Answer 17

only one copy of the dominant allele is needed for it to be expressed

Question 18

what does recessive allele mean?

Answer 18

you have to have two recessive alleles for it to be expressed, it is only expressed if there is no dominant alleles present.

Question 19

what does homozygous mean?

Answer 19

you have two of the same allele

Question 20

what does heterozygous mean?

Answer 20

you have two different alleles for one thing

Question 21

what is a homologous pair?

Answer 21

Every chromosome has matching pairs, one from mum and one from dad

Question 22

what can also cause mutation?

Answer 22

radiation, things you ingest i.e cigarettes

Question 23

what two things effect the appearance of an organism?

Answer 23

1. Genes (inherited characteristics)

2. The effects of the environment in which is lives

Question 24

what is a phenotype?

Answer 24

Observable characteristics of an organism

Question 25

what is a genotype?

Answer 25

The combination of alleles an organism

Question 26

what is meant by co-dominance and what is an example?

Answer 26

condition where both alleles are expressed in the phenotype

- an empale is when flowers have a red allele and a white allele and the flower produced is pink

Question 27

how do you identify co-dominance in punnet squares?

Answer 27

we use the subscript of the first letter of the colour (carrying on from the example)
Cr - is a red flower
Cw - is a white flower
- for a fully red flower the genotype would be CrCr
- A fully white flower the genotype would be CwCw
- CwCr would mean the flower is pink

Question 28

what is a polygenic trait?

Answer 28

Height is controlled by many genes, so there is a scale and it is therefore a continuous type of data. Height is something effected by both genes and environment, all polygenic traits are effected by both

Question 29

an example of monohybrid inheritance

Answer 29

blood, there are certain blood groups and you can only get certain ones with the alleles. and it is controlled by a single gene

Question 30

how is the sex of a person determined?

Answer 30

XX female
XY male
females only carry XX and males carry one or the other

Question 31

diploid and haploid number of chromosomes in human cells?

Answer 31

46 is diploid

23 is haploid

Question 32

what is the process of evolution by means of natural selection?

Answer 32

the more advantages traits are the ones that better adapt and will survive and reproduce. the favourable traits are passed through generations.

Question 33

what is a genetic diagram?

Answer 33

the one that takes longer and is bigger than a punnet square, the one with all the lines

Question 34

sex linked traits?

Answer 34

a sex linked trait is the trait that is carried on only through the X chromosome

Question 35

why can’t the father XY pass down a sex liked characteristic to their sons XY?

Answer 35

because the father can only pass down a Y chromosomes to their son, and the Y chromosome doesn’t carry and sex linked traits

Question 36

how do you write sex linked traits?

Answer 36

the X and Y with a subscript of the first letter of the trait.

Question 37

what is mitosis?

Answer 37

mitosis makes genetics identical cells, they make somatic cells
this type of cell division can be found everywhere
mitosis creates diploid cells

Question 38

what is meiosis?

Answer 38

is exclusively for gametes, sex cells, theses happen in only specific cells. This creates genetically unique cells. meiosis creates haploid cells

Question 39

how does genetic mutation cause faulty enzyme function?

Answer 39

it might alter the shape of the protein if there is a piece of genetic code missing, and the substrate might not fit properly and therefore will not function as an enzyme.

Question 40

difference between mitosis and meiosis?

Answer 40

mitosis

• 2 daughter cells produced
• Happens everywhere in the body
• Produces genetically identical cells, somatic
• Diploid cells
• Cells divide once

meiosis

• 4 daughter cells produced
• Happens only in sex gametes
• Genetically varied cells
• Haploid cells
• Creates variation
• Cells divide twice
• Chromosomes are rearranged

Question 41

how is code read?

Answer 41

• code it is read in threes

Question 42

where does transcription happen?

Answer 42

nucleus of the cell

Question 43

where does translation take place?

Answer 43

cytoplasm and the ribosomes

Question 44

what is a codon?

Answer 44

the complementary triplet of code, mRNA

Question 45

what is a anticodon?

Answer 45

the triplet of unpaired bases, tRNA

Question 46

what are other types of RNA?

Answer 46

transfer RNA, tRNA, ribosomal RNA, rRNA, and messenger RNA, mRNA

Question 47

what is different about RNA, compared to DNA?

Answer 47

• RNA is single stranded

- RNA contains uracil instead of thymine