inheritance and variation Flashcards
1
Q
sexual reproduction?
A
- 2 parents
- gametes
- inherit genes from both parents
- variation increases survival chances
2
Q
asexual reproduction?
A
- 1 parent
- cells divide by mitosis
- produces genetically identical offspring
- no genetic variation- clones produced
- growth and repair of tissues
3
Q
DNA?
A
- polymer made of 2 strands (double helix)
- chromosomes made of DNA
- gene is a section of DNA that codes for a specific protein
- genome= all genes in an organism
4
Q
zygote?
A
46 chromosomes in 23 pairs
5
Q
cystic fibrosis?
A
- inherited from both parents
- parents can be carriers but not have it
- caused by recessive allele
- causes thick, sticky mucus to accumulate in lungs and digestive system
- causes lung infections, problems with breathing, problems with digestion and absorption.
6
Q
polydactyl?
A
extra fingers or toes
- caused by dominant allele
- passed down by one parent
7
Q
embryo screening?
A
used to detect genetic defects in early stage embryos
8
Q
advantages of embryo screening?
A
- helps to stop suffering
- laws in place to prevent it going too far
- allows the pick healthiest embryo
- parents cannot pick the sex of the embryo (unless for medical reasons)
9
Q
disadvantages of embryo screening?
A
- may get to a point where everyone wants to pick the best embryo ‘desirable’ one (eg blue eyes and blonde hair)
- rejected embryos are destroyed (could have been a baby)= unethical
- implies people with genetic disorders are ‘undesirable’= increases prejudice
- screening is expensive
10
Q
alleles?
A
different forms of the same gene
- eg eye colour
11
Q
recessive?
A
characteristic only expressed when 2 of the same alleles are present
- eg bb
12
Q
dominant?
A
characteristic expressed when 1 or both alleles are present
- eg BB or Bb
13
Q
homozygous?
A
2 of the same allele
- eg bb or BB
14
Q
heterozygous?
A
2 different alleles
- eg Bb
15
Q
Phenotype?
A
genes expressed in the physical characteristics
- eg brown eyes
