Genetic inheritance

Question 1

What is a gamete

Answer 1

reproductive cells of parents - sperm and ova

has 23 chromosomes

Question 2

What is zygote

Answer 2

new cell formed by conception

contains full complement of DNA [half from sperm, half from ova]

Question 3

What is role of DNA?

Answer 3

to give genetic information in each cell

Question 4

What are genes?

Answer 4

segments of DNA that code for individual traits

Question 5

What are chromosomes?

Answer 5

Storage structures for DNA
rod like structures visible in cell nucleus
46 chromosomes [in 23 pairs]

Question 6

What is mitosis?

Answer 6

creation of new cells
each chromosome replicates to form two chromosomes with identical genetic blueprints. As cell divides, one member of each pair becomes a member of each daughter cell. Complete genetic endownment is replicated across almost every cell.

Question 7

What is meiosis?

Answer 7

halves number of chromosomes in cell.
Chromosomes pair up and copy, then break into smaller pieces before ‘crossing over’ [randomly exchanging material] and creating new chromosomes with new hereditary combinations.
New chromosomes divide into two separate cells, then again to create 4 cells.
each has unique genetic material
each has 23 chromosomes.

Question 8

What is genotype?

Answer 8

specific genetic information a person inherits that has the potential to influence their observable physical and behavioural characteristics

Question 9

What is phenotype?

Answer 9

traits as displayed or expressed [genotype + environment]

Question 10

What is dominant gene?

Answer 10

influences a child’s phenotype even if paired with a recessive gene

Question 11

What is a recessive gene?

Answer 11

Will only influence a child’s phenotype if paired with another recessive gene

Question 12

What are alleles

Answer 12

two alleles for each gene. Different alleles produce variation in inherited characteristics

Question 13

What are homozygous genes?

Answer 13

alleles for a trait are identical

Question 14

what are heterozygous genes?

Answer 14

alleles for trait are different

Question 15

What are polygenic traits

Answer 15

most traits are polygenic - rely on many genes

Question 16

How many male zygotes are formed at fertilisation, as compared to female?

Answer 16

30% more

Question 17

How many male babies are born, cf female

Answer 17

6%

Question 18

What causes vulnerability to male babies?

Answer 18

could be that X chromosome [longer than Y] holds more genetic information, and therefore if there is a weakness can’t be compensated by other gene on Y

Question 19

What are four genetic abnormalities

Answer 19

chromosome abnormality
dominant gene disorders [eg huntingtons]
recessive gene disorders [eg sickle cell disease]
multifactorial [polygenic] - congenital disease

Question 20

What is downs syndrome?

Answer 20

Trisomy 21 - extra 21st chromosome

Question 21

What is PKU?

Answer 21

phylketonuria, recessive disorder - two recessive alleles, can’t process proteins. leads to low level intellectual disability. can be influenced by diet

Question 22

What is genetic counseling?

Answer 22

helps parents assess risk of bearing child with genetic defect

Question 23

What is behavioural genetics?

Answer 23

study of nature/nurture interaction

Question 24

What is Range of Reaction in behavioural genetics?

Answer 24

range of possible phenotypes - depends on environment

Question 25

What do adoption studies offer

Answer 25

Dissimilar genetics + similar environment; how do genetics determine outcome

Question 26

What do linkage and association studies offer?

Answer 26

identifying individual genes [eg heart disease], trying to find difference in DNA between those who suffer and those who don’t