B6 Flashcards
what does DNA stand for?
deoxyribonucleic acid
what does DNA contain?
coded information that determines what inherited characteristics you have.
where is your DNA found?
in the nucleus of animal and plant cells in very long structures called chromosomes.
what is the structure of a DNA strand called?
a double helix
what does each gene code for and what does it DNA do to contribute to it?
each gene codes for a specific sequence of amino acids which put together to make a specific protein. DNA determine what proteins the cell produces.
what is a genome?
a term for the entire set of genetic material in an organism.
in what ways is the understanding of human genomes an important tool for science and medicine?
- allows scientists to identify genomes linked to disease and could help develop new treatments
- scientists can look at genomes and trace the migration patterns of populations.
in sexual reproduction, the mother and father produce gametes through what process?
meiosis
why does a human offspring inherit features from both parents?
because it retrieves a mixture of chromosomes from both parents (23 from each fuse together to create a full pair of 46)
in asexual production, what is produced? why?
genetically identical cells.
because there’s only one parent so the new cell has exactly the same genetic information as the parent cell. this is called a clone of the parent.
describe the process of meiosis.
- before the cell divides and duplicates, its genetic information forms two armed crossbones which arrange themselves into pairs. (in the centre)
- in the first division, the pairs are pulled apart so each new cell only has one copy of each chromosome (some mother some father)
- in the second division, the chromosomes are pulled apart
- in the end, you have four gametes, each only a single set of chromosomes. they’re all genetically indifferent.
what chromosomes do men have and what chromosomes do women have?
men- XY
women- XX
what are alleles?
different forms of the same gene which can be dominant or recessive.
what is the different between homozygous and heterozygous?
homozygous- when two alleles for a particular gene are the same
heterozygous- if two sets of alleles for a particular gene are different.
what are the two different alleles? what do they determine?
dominant allele- even if the two alleles are different, the dominant allele still determines the traits (Bb or BB)
recessive allele- allele must be present in both chromosomes for it to develop (bb)
what is a genotype?
the combination of alleles and genes an organism has
what is a phenotype?
the result of your genotype. when your allele work ay a molecular level to determine what characteristics you have.
what is an inherited disorder caused by a recessive allele?
cystic fibrosis- genetic disorder of the cell membrane
what does cystic fibrosis cause and how common is it?
causes a thick sticky mucus in the air passages and pancreas. its carried by 1 in 25 people however is very rare as it requires both parents to have the gene for it.
what is an inherited disease caused by a dominant allele?
polydactyly- born with extra fingers or toes
what is polydactyly and how common is it?
genetic disorder meaning you are born with extra fingers of toes. more common as it only requires one parent to pass it down.
what can embryos be screened for during in vitro fertilisation (IVF)? And how?
genetic disorders
by removing a cell from each embryo to analyse its genes.
what are some ethical or moral concerns surrounding embryonic screening.
- implies that people with genetic disorder are undesirable which could lead to prejudice
- people believe IVF is done so people can choose their most desired child
- screenings expensive
why are some people supportive of IVF?
- helps to stop people suffering
- treating disorders costs the gov. and tax payers a lot of money
- there are laws preventing extremes e.g what sex you baby is.
what is genetic variation cause by?
your genotype (all the alleles and genes an organism has) which effects the phenotype (displays your characteristics)
what are mutations?
a random change in the organisms DNA that can be inherited. it causes a change I’m the genome (gene is altered)
what is Darwins Theory Of Evolution?
that all of todays speeches have evolved from simple life forms that first started to develop 3 billion years ago
what is the development of new species called?
speciation (phenotypes changes so much due to natural selection that a completely new species is formed.
what does extinction mean?
when no individuals of a species remain.
what are some reasons for species to become extinct?
- quick changes in the environment
- new predators
- new diseases
- cant compete with other new species for food
- a natural disaster or catastrophic event.
