inheritance

Question 1

gene

Answer 1

can separate and combine, mutate and code for the production of specific polypeptides

Question 2

homozygous

Answer 2

If both alleles of a gene are the same they are homozygous e.g. TT, tt.

Question 4

chromosome

Answer 4

formed by a single molecule of DNA and exist in homologous pairs to hold the genetic code in form of genes

Question 5

what is an allosome

Answer 5

sex determining chromosome NOT AUTOSOME!!!!!!!

Question 6

locus

Answer 6

position of a gene on a chromosome

Question 7

alleles

Answer 7

alternative forms of genes

Question 8

dominant

Answer 8

Of the pair of alleles in a monohybrid cross, the one that always produces an effect on the phenotype of the organism when present is the dominant allele.

Question 9

recessive

Answer 9

The allele that produces an effect on the phenotype only when present as an identical pair is the recessive allele

Question 10

co-dominant

Question 11

phenotype

Answer 11

The appearance of an organism – it is determined by the genotype.

Question 12

variation

Answer 12

differences between individuals of the same species, caused by genes, environment or both

Question 13

discontinuous variation

Answer 13

clear-cut differences in a characteristic e.g. tall and dwarf pea plants.

Question 14

what is discontinuous variation caused by?

Answer 14

one of more forms of a single gene - alleles

Question 15

continuous variation

Answer 15

no clear groups- characteristics form a range of values e.g. height.

Question 16

what is continuous variation caused by?

Answer 16

several genes acting together - polygenic

Question 17

what can homozygous individuals called?

Answer 17

pure breeding - does not tell you if it is dominant or recessive.

Question 18

what is monohybrid inheritance?

Answer 18

a single characteristic controlled by one gene

Question 19

what is the law of segregation

Answer 19

the characteristics of an organism are determined by alleles which occur in pairs. only one of a pair of factors can be present in a single gamete

Question 20

what is the ratio in F2 in codominant alleles?

Answer 20

1:2:1

Question 21

what blood groups are co-dominant?

Answer 21

A and B

Question 22

what blood group is recessive?

Answer 22

O is recessive (to A and B)

Question 23

what is dihybrid inheritance?

Answer 23

the inheritance of two characteristics coded for by two separate genes

Question 24

what is linkage of genes?

Answer 24

any two genes that occur on the same chromosome are usually inherited together.

Question 25

what is a linkage group?

Answer 25

all the genes on the same chromosome

Question 26

what happens to linked genes during cell division?

Answer 26

linked genes remain together (NOT following Mendel's 2nd law of independent assortment)

Question 27

how is sex determined?

Answer 27

by a pair of chromosomes. Other chromosomes are called autosomes

Question 28

In humans, which sex chromosomes are homologous and non-homologous?

Answer 28

female - homologous (XX) male - non-homologous (XY)

Question 29

What is the ratio for male to female gametes?

Answer 29

1:1

Question 30

What are the differences between the X and Y chromosome?

Answer 30

The X chromosome is very small and contains very few genes, but the X chromosome is large and contains thousands of genes for important proteins

Question 31

What kind of proteins are found in the X chromosome?

Answer 31

1. Rhodopsin - a light absorbing pigment found in the membrane of retina photoreceptor cells 2. blood clotting proteins 3. muscle proteins

Question 32

Which chromosome are recessive alleles carried?

Answer 32

The X chromosome

Question 33

How is the haemophiliac (recessive) allele carried?

Answer 33

- Male can't pass on the allele to his sons as they receive the Y chromosome. - All daughters receive the recessive allele so will be carriers. They have a 50% chance of passing the condition to their offspring

Question 34

What is Haemophilia caused by?

Answer 34

- caused by a recessive allele on X chromosome - gene codes for factor VIII a protein involved in blood clotting

Question 35

why is haemophilia so dangerous?

Answer 35

potentially lethal condition-inability of blood to clot leads to slow persistent bleeding

Question 36

How can haemophiliacs lead near normal lives?

Answer 36

It is possible to extract Factor from donated blood

Question 37

What is Duchenne muscular dystrophy (DMD)?

Answer 37

a progressive loss of strength by muscle degeneration

Question 38

what is the cause of DMD?

Answer 38

- recessive allele on X chromosome - a mutation in the gene that codes for dystrophin

Question 39

What is the issue if dystrophin is absent in DMD?

Answer 39

absent muscle cells are easily damaged. progressive muscle weakness leads to serious medical problems with issues relating to the heart and lungs

Question 40

What is the lifespan of those with DMD?

Answer 40

Young men with Duchenne typically live into their late 20s