cell reproduction, mutations, inheritance

Question 1

3 types of reproduction

Answer 1

asexual - binary fission - mitosis sexual - meiosis

Question 2

binary fission steps

Answer 2

1. single cell 2. bidirectional replication of circular dna - chromosomes replicate - moves to opposite sides and cell grows 3. cell elongates - cleavage furrows form 4. cell splits - 2 identical daughter cells are formed each eith a copy of the genetic material

Question 3

sexual vs asexual

Answer 3

sexual: - 2 parents - fusion or female and male cells - parents and offspring not identical - slower - variation asexual: - 1 parent - no gametes produced - parent and offspring identical - faster - no variation

Question 4

vegetative propagation

Answer 4

plant asexual reproduction runners: side branch that grow along the surface, roots grow down developing new plants eg strawberriers tubers: provide energy and nutrients for regrowth eg potatoes, roots then tuber bulb: short stem with fleshy leaves, onion, onion then roots

Question 5

variation and types

Answer 5

1.independent assortment of chromosomes in meiosis - separation of chromosome pairs at meiosis 2.random mating and fertilisation of gametes - punnet squares - possibly recombinations at fertilization 3.crossing over during meiosis - swap genes from 2 homologous chromosomes - can separate linked genes 4.mutations - changes in gene or chromosome

Question 6

IPMATC

Answer 6

I - dna replication occurs, chromosomes not visible P - nuclear membrane disappears - dna shortens into chromosomes - cell has 2 chromosomes each has double dna - 2 chromatids joined by a centromere M - centrioles move to each pole forming a spindle between them - spindle fibres form - chromosomes line up along equator A - double stranded chromosomes spilt into 2 single chromosomes - single chromosomes move to opposite poles T - 2 new nuclear membranes form around the chromosomes - 2 nuclei are formed C - cell cytoplasm splits - 2 new cells form - each with 2 single chromosomes

Question 7

steps of mitosis

Answer 7

IPMATC

Question 8

steps of meiosis

Answer 8

IPMATC PMATC

Question 9

fertilization

Answer 9

• fusion of sperm and egg cell - halves the number of chromosomes from 46 to 23 - resulting cell has 46 each (zygote) - sperm and egg = haploid gametes - zygote = diploid - produces genetic variation - 2 parents

Question 10

mitosis vs meiosis

Answer 10

mitosis: - cell division for growth and repair - takes place in somatic cells - one cell division - asexual - daughter cell = diploid - no variation - diversity narrowed - produces tissue culture meiosis: - cell division for producing gametes - takes place in gonads/reproductive organs - 2 cell divisions - daughter cell = haploid - sexual - diversity increased - produces new organisms

Question 11

continuity of life

Answer 11

• for life to continue genetic information must be transferred to the next generation - location of particular genes on a chromosome is referred to as a locus - in homologous chromosomes corresponding genes found in same locus - alternate forms of the same genes are called alleles

Question 12

the cell cycle

Answer 12

• sequence of events from one cell division to another - life cycle of cell interphase = G1 phase (cell growth before replication), S phase (synthesis & replication), G2 phase (cell prepares for division) M phase = mitosis, cytokinesis G0 phase - withdrawn from cell cycle, not preparing to replicate - terminally differentiated cells e.g. nerve cell - can enter under certain circumstances checkpoints: first - beginning of interphase, pass if the cell is large enough, sufficient nutrients available second - end of interphase, pass if cell is large enough and replication is successful third - pass if all chromosomes attached to mitotic spindle

Question 13

non - disjunction

Answer 13

chromosome can fail to separate resulting in abnormal numbers of chromosomes in gametes

Question 14

aneuploidy

Answer 14

• results in abnormal number of sex chromosomes turner syndrome - 1 sex chromosome XO Klinefelter syndrome - 1 extra chromosome XXY trisomy - 1 extra chromosome down - trisomy 21 edward - trisomy 18

Question 15

mutations

Answer 15

change in gene sequence by adding or deleting nucleotides

Question 16

causes of mutations

Answer 16

spontaneous - random - errors in replication or division induced - environment - radiation - poison - diet

Question 17

location of mutations

Answer 17

gametic - in sex cells - affects all cells - inherited somatic - in autosomal cells - harmless or may cause cancer - not inherited

Question 18

strength of mutations

Answer 18

lethal - deadly harmful - non lethal e.g. down syndrome silent - harmless with no noticeable affect beneficial - useful particularly in new environment

Question 19

gene mutations

Answer 19

• arise when a gene fails to make an exact copy of itself during replication substitution missense: - produces 1 new amino acid - may change function - changes one nucleotide substitution nonsense: - produces a stop codon - early termination of polypeptide chain - short, disfunctional insertion: frame shift - 1 base is inserted - reading frame shifts resulting in new amino acids rom the point of insertion - resulting protein will be different and non-functional deletion: frame shift - 1 base deletion - can reinsert somewhere else, amino acids between these points change - if not reinserted affects all amino acids after - effects depend on how many amino acids were affected

Question 20

mutagen

Answer 20

agent capable of inducing a mutation uv rays

Question 21

chromsome mutations

Answer 21

duplication - extra copy is made of a section of chromosome and inserted into the same or another chromosome inversion - breaks in 2 places and then rotates 180 degrees before rejoining - genes neither gained or lost - still function normally deletion - breaks in 2 places, falling out - leads to absence of genes insertion - piece of chromosome is added translocation - section breaks off and reattaches to another chromosome, non - homologous changes in chromosome number - anapolidy : loss / gain f chromosome - polyploidy : loss / gian of chronometer set

Question 22

phenotype variation

Answer 22

morphological - variation in shape and structure include internal anatomy biochemical - variation in chemical structure - composition of organisms e.g. proteins, lipids physiological - variation in ways organisms carry out metabolism and maintain their bodily processes behavioral - differences in ways organisms perceive, think and react

Question 23

punnet squares

Answer 23

• tool used to help predict the outcome of genetic crosses - each outcome has equal chances of occurring

Question 24

pedigree

Answer 24

• family tree of genetic history square = male circle = female colored in = affected

Question 25

determine if trait is recessive or dominant (pedigree)

Answer 25

- need to find the triangle - no triangle can't tell - disease on bottom = recessive - disease on top = dominant

Question 26

inheritance rules

Answer 26

autosomal recessive : appears in both sexes equally - tend to skip a generation - e.g. cystic fibrosis, sickle cell anemia autosomal dominant : appears in both sexes equally - unaffected parents do not transmit the trait X-linked recessive : affects more males - affected fathers never pass to sons but all daughters are carriers

Question 27

allele

Answer 27

2 forms of the same gene - dominant - recessive

Question 28

dominant

Answer 28

- stronger - expressed - shown as capital

Question 29

recessive

Answer 29

- allele that is masked - shown as lower case

Question 30

trait

Answer 30

- any characteristic that can be passed from parent to offspring

Question 31

heredity

Answer 31

passing of traits from parent to offspring

Question 32

genetics

Answer 32

study of heredity

Question 33

genotype

Answer 33

gene combination for trait

Question 34

phenotype

Answer 34

physical feature resulting from genotype

Question 35

P generation

Answer 35

parental

Question 36

F1

Answer 36

first filial offspring of P

Question 37

F2

Answer 37

second filial offspring of F2

Question 38

locus

Answer 38

specific position of gene on a chromosome

Question 39

carrier

Answer 39

carry the trait but don't express the disorder

Question 40

test cross

Answer 40

unknown dominant phenotype is crossed with the homozygous recessive phenotype - if homozygous 100% with show dominant phenotype - if heterozygous 50% will have dominany phenotype

Question 41

incomplete dominance

Answer 41

offspring show a blend of traits red + white = pink

Question 42

codominance

Answer 42

- offspring expresses both traits red + white = red and white

Question 43

sex linkage

Answer 43

- gene on sex chromosome - X linked - males have higher chance of getting it - mutations include colour blinders, muscular dystrophy

Question 44

monogenic

Answer 44

- characteristics determined by 1 pair of genes e.g. Ee

Question 45

polygenic

Answer 45

- more then one gene - phenotype shows variation - environment also influences phenotype - eg weight

Question 46

blood types

Answer 46

Type A: AA, AO - donate to A, AB - get from A,O Type B: BB,BO - donate to B, AB - get from B,O Type AB : AB - donate to AB - get from anyone Type O : OO - donate to anyone - get blood demo O (lower case i)

Question 47

multiple alleles

Answer 47

more then 2 different forms of the same gene

Question 48

continuous vs discontinuous variation

Answer 48

continuous - range of measurements e.g. height discontinuous - certain categories e.g. blood