Genetics Flashcards
What is the difference between asexual and sexual reproduction and how do they work
Asexual - a type of reproduction involving only one parent. It uses the process of mitosis to create identical copies of the parent cell
Sexual - the formation of new organisms by combining the genetic material of two organisms. It uses the process of meiosis, which creates gametes
What are facts about asexual reproduction
Requires one parent
Offspring is identical to parent
Takes a shorter time
Takes less energy
Unable to adapt to surroundings
What are facts about sexual reproduction
Requires two parents
Offspring is unique to the parent
Takes a longer time
Takes more energy
Able to adapt to surroundings
What are gametes
Sex cell
Sperm in males and eggs in females (animals)
Pollen in males and eggs in females (flowering plants)
What are zygotes
A fertilised egg cell
What is fertilisation and how does it work
The fusion of the nucleus of a male gamete with the nucleus of a female gamete
When the two gametes combine, they merge the two sets of chromosome to have 46
This produces a new cell called a zygote, which will mature into an embryo. The number of cells increase by mitosis, and as the embryo develops, the cells begin to differentiate
What is DNA, how many strands does it have and what shape is it
The material inside the nucleus of cell carrying the genetic information
2
A double helix
What are chromosomes
Long threads of DNA which is made up of many genes
What a gene
A small section of DNA in a chromosome
What an allele
Different version of the same gene
What is the difference between a genotype and a phenotype
Genotype - the characteristic an organism has, usually written in letters
Phenotype - the characteristic an organism has, usually written in words
What is the difference between a dominant and recessive allele
Dominant - will show a characteristic if inherited from one or both parents. Represented by a capital letter
Recessive - will show a characteristic if inherited from both parents. Represented by a lowercase letter
What is the difference between a homozygous dominant, homozygous recessive and heterozygous
Homozygous dominant - a genotype with two dominant alleles, e.g. AA
Homozygous recessive - a genotype with two recessive alleles, e.g. aa
Heterozygous - a genotype with on dominant and recessive allele, e.g. Aa
What are the sex chromosomes for males and females
Males - xy
Females - xx
What is Cystic Fibrosis and how is it inherited
An inherited genetic disease that mainly affects the lungs and digestive system
Caused by a recessive allele. Both parents have to be carriers for their child to have a chance of inheriting it
CC - not affected by CF
Cc - carrier of CF
cc - affected by CF
What is Polydactyly and how is it inherited
An inherited condition in which a person has extra fingers or toes
By a dominant allele. Only one parent needs to have it for their child to have a chance of inheriting it
PP - affected by polydactyly
Pp - affected by polydactyly
pp - not affected by polydactyly
What are the genetic tests
Antenatal - to analyse an individual’s DNA or chromosomes before they are born
Neonatal - analysing a sample of blood that is taken from pricking a baby’s heel
Pre-implantation genetic diagnosis - the embryos are checked to see if they have any particular conditions before implantation in IVF
What are the limits of genetic testing
False positive - A genetic test that wrongly detected a certain allele or faulty chromosome
False negative A genetic test has failed to detect a certain allele or faulty chromosome
What are the sources of variation
Genetic - some features can be passed on from your parents, e.g. eye colour and blood group
Environment - some features can be influenced by your surroundings, e.g. hair colour, scars and tattoos
Combined - e.g. weight, height and behaviour
What are the types of variation
Continuous - a range of values which can have values in between not in groups, e.g. height, weight, milk yield
Shown as a line graph or histogram
Discontinuous - data that comes in groups and not a range, e.g. blood group and eye colour
Shown as a bar chart
What is the difference between variation and mutation
Variation - within genes that lead to different genotypes, and this can be seen by a different phenotype
Mutation - a change in a gene or chromosome
What is selective breeding and how does it work
When humans breed plants and animals for particular genetic characteristics
Decide which characteristics are important enough to select
Choose parents that show these characteristics from a mixed population. They are bred together.
Choose the best offspring with the desired characteristics to produce the next generation
Repeat the process continuously over many generations, until all offspring show the desired characteristics
What are some characteristic you want in plants and animals
Plants:
Disease resistance in food crops
Wheat plants that produce a lot of grain
Large flowers
Animals:
Animals that produce a lot of milk and meat
Chickens that lay large eggs
Domestic dog that have a gentle nature
What are the benefits and risks of selective breeding
Benefits:
New varieties may be economically important, by producing more or better quality foods
Animals can be selected so that they don’t cause harm, e.g. a cattle without horns
Risks:
Reduced genetic variation can make the susceptible to the same disease/insects
Can create physical problems due to something not forming right
