You and your genes B1 Flashcards
where is DNA stored?
nucleus
what unit controls a cells function?
genes
what type of biochemical do gene’s code for?
proteins
DNA is a very long molecule found in the nucleus. what is the condensed form called?
chromosomes
characteristics can be formed by 3 factors. what are they?
- genetic
- environmental
- genetic and environmental
how many chromosomes does a normal cell contain?
23 pairs
how many chromosomes do gametes contain?
23
what do we call different versions of a gene?
alleles
how many of these versions can an organism have?
2
if an individual has 2 of the same allele, they are…
homozygous
if an individual has 2 different alleles, they are…
heterozygous
sexual reproduction requires genetic information from how many people?
2
siblings are not identical because…
parents alleles are combined differently so there’s variation
what are the 2 terms for different alleles that refer to the relative strength of an allele?
dominant and recessive
what are the male and female determination chromosome pairs?
male: XY
female: XX
what chromosome contains the gene that triggers the development of male characteristics?
Y chromosome
what is that gene called?
SRY
what does the term genotype mean?
the combination of alleles of an individual organism
what does the term phenotype mean?
the observable characteristics of an organism
name two diseases that are caused by a single faulty gene, giving one example of the disease being dominant and one recessive
Huntingdons disease - dominant
Cystic fibrosis - recessive
what symptoms do Huntingdons disease present?
- clumsiness
- memory loss
what symptoms do cystic fibrosis present?
- chest infections
- difficultly in digesting food
what term is given to an individual that heterozygous for a recessive disease causing gene?
a carrier
what are the implications of running a genetic screen on a pregnant woman need to be considered before the procedure is carried out?
risk of miscarriage as a result of a cell sampling for the genetic test
what are some of the implications of testing embryos prior to implantation?
parents could choose the characteristics of the child
describe asexual reproduction and some of the types of organisms that can carry it out
bacteria, plants and some animals can reproduce asexually to form clones
what is a clone?
individuals with identical DNA
what factors might cause differences between clones?
environmental factors
describe a way in which clones occur in animals
naturally when cells of an embryo separate
why is the medical industry interested in developing our understanding of stem cells?
potential to treat some illnesses
where are genes found?
in our chromosomes
what does the nucleus do?
control activities of a cell
environmental characteristics
climate, diet, lifestyle, culture
how do plants, bacteria and animals form clones?
reproduce asexually
adult stem cell
unspecialised cells that can develop into many types of cells
embryonic stem cells
unspecialised cells that can develop into any cell
dominant allele
two copies needed to have the feature it produces
recessive allele
only needed to have the feature it produces
