inheritance

?
  • Created by: lridgeway
  • Created on: 07-11-18 19:58
What is a gene?
section of DNA which codes for a polypeptide
1 of 44
What is the location of the gene on the chromosome called?
locus
2 of 44
In homologous pairs the genes are always on the same loci what varies?
alleles
3 of 44
What is an allele?
different form of the same gene
4 of 44
What is a cross?
the deliberate mating of two organisms for genetic analysis
5 of 44
What is a monohybrid cross?
a cross with one gene
6 of 44
What is a dihybrid cross?
a cross with two different genes
7 of 44
What are homologous chromosomes?
chromosomes that have the same genes along their length
8 of 44
What is a genotype?
the combination of alleles for the gene
9 of 44
What is phenotype?
the characteristic expressed by the gene
10 of 44
What does the term dominant mean?
an allele which is always expressed when present
11 of 44
What does the term recessive mean?
only expressed if both alleles present
12 of 44
What does heterozygous mean?
two different alleles for the gene
13 of 44
What does homozygous mean?
two of the same alleles for the gene
14 of 44
What must you do when carrying out a cross?
choose suitable symbols (always letters, usually the dominant feature letter used and that is the capital one) and label and state parent genotype and phenotype and show gametes
15 of 44
State Mendel's first law
Law of segregation which states that there is a 50% chance of getting either allele/gene as its due to random chance
16 of 44
State Mendel's second law
Law of independent assortment which states that the genes don't affect each other and influence the other
17 of 44
What happens when genes are on the same chromosomes?
genes are linked and some gamete combinations aren't possible as independent assortment does occur
18 of 44
What happens is were to do chi squared test with linked genes?
the findings do not follow Medellin laws so when carrying out a chi squared test would find a significant difference and reject the null hypothesis
19 of 44
What can, but rarely, occur in linked genes?
crossing over (chiasmata) occurs and genes switch so the combinations previously not possible are possible and may occur. this is less likely if genes are closer are chromosomes
20 of 44
What is a pair of same size identical genes called?
autosomes
21 of 44
What is a pair of different size identical genes called?
heterosomes
22 of 44
What do the genes on the Y chromosome do?
turn on or off genes on other chromosomes
23 of 44
What are all the chromosomes on an individual called?
karyotype
24 of 44
Explain sex linkage
some alleles are found on the sex chromosomes and are therefore affected by gender e.g gene for colourblindness is found on x chromosome
25 of 44
What is co-dominance?
both alleles are expressed individually if the organism is heterozygous, for example if t was colour of a cow and the alleles are red and white then both alleles would be expressed
26 of 44
What is incomplete dominance?
when neither allele is completely dominant, heterozygous individuals will have a blend (intermediate) of the characteristics
27 of 44
How can you do a dihybrid cross the easier way?
do the two characteristics in two monohybrid crosses and work out the fractions of each ones and then times them to get the fractions of the 4 combinations
28 of 44
When do most mutations occur?
crossing over during late prophase 1 in meiosis
29 of 44
When else can mutations occur?
nondisjunction
30 of 44
What is nondisjunction and what causes it?
It is when gametes are are formed which have too little or too many chromosomes. This is caused by chromosome pairs not separating properly during either prophase
31 of 44
What are point mutations and why are some silent mutations?
point mutations are changes in a single base pair and silent ones don't always effect the phenotype
32 of 44
What mutagens increases point mutations?
x-rays, gamma rays, UV radiation and chemicals (poly-cyclic hydrocarbons)
33 of 44
Define trisomy
When a gamete has 3 copies of a chromosome
34 of 44
Outline how sickle cell anaemia occurs
Changes secondary and tertiary structure of haemoglobin which causes molecules to interact forming a fibre and this reduces oxygen carrying capacity. The blood cells become sickle shaped due to this crystallisation to form fibres.
35 of 44
What does sickle cell anaemia cause?
Fatigue/breathlessness and the cells get stuck in capillaries which is painful
36 of 44
What is cancer?
too much mitosis caused by a mutation
37 of 44
What are the two types of cancer?
Benign (doesn't spread quickly) and malignant (spreads and looks less aggregated so is close and loosely joined)
38 of 44
How is cell division normally controlled?
Growth factor (hormone) is released, this binds to receptor and triggers a series of enzymes to cause DNA transcription, which leads to cell division
39 of 44
What mutations can cause cancer?
mutation on receptor causing pathway to be triggered without growth factor, or too much growth factor produced which oncogenes cause
40 of 44
What are proto-oncogenes and oncogenes?
proto-oncogenes are genes that can cause cancer if they mutate, oncogenes are those genes when they mutate.
41 of 44
What is epigenetics?
genes that are effected without changing the nucleotide sequence
42 of 44
What makes a gene more likely to be expressed?
if DNA becomes methylated the DNA becomes more loosely coiled and is more likely the gene is expressed even if the gene is on
43 of 44
What makes a gene less likely to be expressed?
if histones become methylated the DNA coils tighter around the histone so the gene is less likely to be expressed even if it is turned on
44 of 44

Other cards in this set

Card 2

Front

What is the location of the gene on the chromosome called?

Back

locus

Card 3

Front

In homologous pairs the genes are always on the same loci what varies?

Back

Preview of the front of card 3

Card 4

Front

What is an allele?

Back

Preview of the front of card 4

Card 5

Front

What is a cross?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all DNA, genetics and evolution resources »