B6-inheritance, variation and evolution

Created by

Elle Roberts

Cards (59)

what is a gene?
a small section of DNA found on a chromosome
what is a genome?
entire set of genetic material in an organism
why is the human genome important?
-helps to identify genes that are linked to disease
-helps to develop treatments for these diseases
-can trace the migration of certain populations of people
what is produced in sexual reproduction?
gametes
egg and sperm
how many chromosomes does each gamete contain?
23
how is an offspring produced?
an egg and sperm fuse (fertilise)
why does the offspring inherit features from both parents?
receives a mixture of chromosomes from mum and dad
what does the mixture of genetic information produce?
variation in the offspring
if sexual reproduction produces genetically different cells, what process is used?
meiosis
if asexual reproduction produces genetically identical cells, what process is used?
mitosis
what is asexual reproduction?
there is only one cell which divides a produces a clone of the parent cell
what organisms reproduce asexually?
bacteria
what is the stage before meiosis?
cell duplicates its genetic information forming two armed chromosomes and they arrange into pairs
what is the first stage of meiosis?
first division, chromosome pairs line up in the centre of the cell
what is the second stage of meiosis?
pairs of chromosomes are pulled apart, some of the father chromosomes and some of the mother chromosomes go into each new cell
what is the third stage of meiosis?
second division, chromosomes line up in the centre of the cell, arms of the chromosomes are pulled apart
what is the result of meiosis?
4 gametes, each with a single set of chromosomes. each gamete is genetically different
what are the male chromosomes?
XY
what are the female chromosomes?
XX
what are alleles?
different versions of genes
what is homozygous?
two alleles that are the same
what is heterozygous?
two alleles that are different
what are examples of dominant alleles?
AA Aa
what is an examples of recessive alleles?
aa
what is a genotype?
the combination of alleles you have
what is a phenotype?
the characteristics you have
what allele causes cystic fybrosis?
recessive
what allele causes polydactyly?
dominant
why are people against embryonic screening?
-implies that people with genetic problems are undesirable
-becomes a point where everyone wants to screen the embryo to pick the most desirable one
-expensive
why do people support embryonic screening?
-stops people suffering
-there are laws to stop it going too far
what is an example of an inherited characteristic?
eye colour
blood type
hair colour
what is an example of environmental characteristics?
tattoos
accent
clothing
what is a mutation?
changes to the genome
what is the theory of evolution?
all of todays species have evolved from simple life forms that first started to develop over 3 billion years ago
what is the survival of the fittest? 
organisms with the most suited characteristics for the environment would be more successful competitors and would be more likely to survive and can pass on these characteristics during reproduction
what is speciation?
development of a new species
what are 5 reasons for extinction?
-the environment changes too quickly
-a new predator kills them
-a new disease kills them
-they can't compete with others for survival
-a catastrophic event happens and kills them all
what is selective breeding?
taking the best plants and animals and breed them together to get the best possible offspring
what are examples for why selective breeding is used?
-animals that produce more meat or milk
-crops with disease resistance
-dogs with a good, gentle temperament
-decorative plants with big, unusual flowers
what is the process of selective breeding?
from your group, select the ones with the desired characteristics
2. breed them with each other
3. select the best of the offspring and breed them together
4. continue this over several generations until all offspring have the desirable characteristics