task 1.

Question 1

define cell replication

Answer 1

the process by which cells replicate their genetic material and divide to form new cells.

Question 2

define mitosis

Answer 2

mitosis is a type of cell division where 1 parent cell divides once to produce 2 identical cells.

Question 3

what is the result of mitosis

Answer 3

2 identical daughter cells

Question 4

describe the prophase in mitosis

Answer 4

chromatin shortens and thickens to form chromosomes

Question 5

order of the phases in mitosis

Answer 5

prophase
metaphase
anaphase
telophase
cytokinesis

Question 6

describe the metaphase in mitosis

Answer 6

chromosomes line up individually

Question 7

describe anaphase in mitosis

Answer 7

spindle fibres attach to centromeres

Question 8

describe telophase in mitosis

Answer 8

spindle fibres shorten, centromeres break and chromatids move apart

Question 9

describe cytokinesis

Answer 9

cytoplasm separates, cell and nuclear membrane from chromosomes uncoil

Question 10

importance of mitosis

Answer 10

creates new body cells that is needed for growth, repair and maintenance

Question 11

what are the 3 steps in dna replication

Answer 11

1. unravelling the dna
2. building a new strand
3. forming the dna backbone

Question 12

explain the unravelling of the DNA as part of dna replication

Answer 12

the enzyme DNA helicase breaks the hydrogen bonds between the bases, “unzipping” the double helix into single strands

Question 13

explain the building a new strand as part of dna replication

Answer 13

“semi conservative” process. When DNA is produced, one of the strands in each new DNA moleucle comes fromt he old DNA molecule - reduces the chance of copying a strand incorrectly - dna polymerase helps bind free nucleotides in the cell nucleus to the single strands - meaning an identical copy of the dna strand is produced

Question 14

explain the formation of the dna backbone as part of dna replication

Answer 14

dna polymerase stitches these newly joined nucleotides together so that the sugar-phosphate backbone is formed.

Question 15

what is transcription

Answer 15

an mRNA copy of a gene is made and DNA is used as a template

Question 16

explain the steps of transcription

Answer 16

1. rna polymerase attaches to dna at the desired gene and separates the strands to expose the nucleotides in that region
2. one strand is used as a template to make mRNA strand identical to the other strand, through complementary base pairings
3. free floating nucleotides pair with their complementary bases on the template strand
4. the rna polymerase reaches a stop codon and lets go of the DNA strand (production is complete for prokaryotes)
5. in eukaryotes, introns are spiced out of the strand and exons are stuck together to form the final mRNA strand.
6. mrna molecules leave the nucelus and enter the cytoplasm through nuclear pore

Question 17

what is translation

Answer 17

mRna is converted to a polypeptide chain

Question 18

steps of translation

Answer 18

1. mrna attaches to a ribosome at a particular start codon
2. the mrna molecule is with the correct anticodon pairs up with he mRNA in the ribosomes
3. a second tRNA molecule attaches to the next codon on the mRNA strand
4. the ribosome catalyses the formation of a peptide bond between the two amino acids
5. the ribosome continues to the move along the mrna until is reaches a stop codon
6. the polypeptide chain and mrna strand are released from the ribsome.

Question 19

what is incomplete dominance

Answer 19

two dominant alleles resulting in a blended phenotype

Question 20

e.g. of incomplete dominancę

Answer 20

red flower x white flower = pink hetero flower

Question 21

what is codominance

Answer 21

two dominant alleles resulting in both phenotypes being expressed athe the same time

Question 22

e.g. of codominance

Answer 22

black chicken x white chicken = heterzygous having both black and white feathers

Question 23

what is sex linked

Answer 23

when an allele is located on the x chromosome

Question 24

e.g. sex linked

Answer 24

haemophilia or colour blindess

Question 25

multiple alleles

Answer 25

occur within genes that have more than two alleles.

Question 26

e.g. multiple alleles

Answer 26

inheritance of human blood groups display