B13 Flashcards

Question

What is a mutation ?

Answer 1

Random change in the sequence of bases in DNA - can be inherited or caused - may be beneficial or have a negative effect on the phenotype of the organism; oftentimes has no effect however

Answer 2

prokaryotes - reproduction via binary fission means that all offspring are clones [] will ALWAYS inherit ALL mutations in the DNA loop of the parent prokaryote [] genetic mutations in plasmids may sometimes be passed on or shared between prokaryotes humans - mutations in gametes have a chance of being passed to offspring (not always) - mutations in mitotically dividing cell DNA will always be passed on [] dangerous as body cells may become cancerous in this way

Answer 3

Genes regulating cell cycle mutate, allowing the cells to divide uncontrollably and rapidly

Answer 4

- substitutions [] one base substituted with another (eg. AGT becomes TGT) [] sometimes changes which amino acid is coded for, which affects the protein made or how well it functions, but not always happens - deletions [] a random base from the sequence is deleted [] all bases shifted up one, meaning that amino acids coded for are different and thus the protein is different or doesn't function - insertions [] a random base is inserted into the sequence [] all bases shifted down one, meaning that amino acids coded for are different and thus the protein is different or doesn't function

Answer 5

- non-coding DNA often controls protein or gene expression via switching genes off/on - mutations can affect how much a protein is expressed (produced by the body) [] this is an example of how diabetes comes about

Answer 6

dominant allele

Answer 7

when two are paired together as a homozygote

Answer 8

All offspring should have the heterozygotic genotype Bb (brown fur, as B is the dominant allele)

Answer 9

- 2 heterozygote offspring (Bb) with brown fur - 2 homozygote offspring (bb) with black fur

Answer 10

- 1 homozygote offspring (BB) with brown fur - 2 heterozygote offspring (Bb) with brown fur) - 1 homozygote offspring (bb) with black fur

Answer 11

- inheritance is RANDOM [] probabilities of the different phenotypes in a theoretical ratio are very different irl - eg. the chance of offspring being a dominant-allele-homozygote may be 80%, whilst all other phenotypes are 20% combined [] genetic information in gametes is unique and randomised during meiosis - too small of a sample

Answer 12

male = XY female = XX

Answer 13

- genetic disorder that is inherited by a DOMINANT allele [] even heterozygous people have the disorder expressed - results in people having extra fingers or toes [] can be removed or kept - doesn't have that big of an effect on daily life

Answer 14

- genetic disorder caused by a RECESSIVE allele [] heterozygous people with an allele for cystic fibrosis don't express the disorder, but are called carriers as they can pass the disorder to their offspring if their partner also has an allele for cystic fibrosis - disorder of the cell membranes that prevents diffusion of certain substances in/out of the cell [] mucus secreted by cells becomes very thick and sticky, and often clogs up organs (especially the lungs and pancreas), affecting their function - many with cystic fibrosis are infertile - treated with physiotherapy, antibiotics and replacement enzymes if the pancreas is clogged [] no cure yet, though scientists hope that genetic engineering will be able to cure the disorder as well as genetic disorders generally

Answer 15

- method of genetic screening of embryos carried out at 15-16 weeks of pregnancy - fluid from the amniotic sac containing foetal cells is retrieved using a needle - these foetal cells can be genetically screened for disorders

Answer 16

- method of genetic screening of embryos, carried out at 10-12 weeks of pregnancy - two methods: transabdominal (cells retrieved using a needle through the abdomen), and transcervical (cells retrieved using a catheter through the cervix and into the uterus) - both methods involve taking a sample of foetal cells from the developing placenta to be genetically screened for disorders

Answer 17

- embryo external to the patient (eg. IVF embryos) - placenta - amniotic fluid

Answer 18

DNA isolated from the cell(s)' nucleus and tested for specific disorders

Answer 19

disadvantages: - screening increases the risk of miscarriage, which is emotionally and physically stressful for the parent(s) - can sometimes give a false positive or negative [] healthy embryos thus may be discarded or aborted mistakenly, or disordered embryos may be allowed to develop and be born - if the embryo tests positive for a disorder, couples have to make the decision to either abort or continue with the pregnancy; emotionally stressful - screening is expensive [] at the moment, is only offered to those with a family history of genetic disorders or older parents whose children are more at risk of genetic disorders - ethical concerns about eugenics or "designer" babies advantages: - people with genetic disorders are more expensive for the government or parents long-term as treatment is often intensive or highly specialised - allows parents who don't want to terminate the pregnancy if the embryo tests positive for disorder to make preparations and accommodations for the child in advance - if the parents cannot afford to raise a child with a genetic disorder, allows them to abort the pregnancy or not implant that embryo and try again for a healthy baby

B13 Flashcards

Reproduction