Biology Flashcards
Gene
Section of DNA that codes for a particular trait or characteristic
Allele
Different form of a gene
Genotype
Pair of alleles present for a characteristic
Phenotype
The physical expression of the alleles
Homozygous
Pair of alleles that produce a characteristic are the same
Heterozygous
A pair of alleles that produce a characteristic are different
Dominant allele
An allele that will always be expressed even when there is only of these
Recessive allele
An allele that will only be expressed when both alleles are of this type
2 types of variation
Genetic variation and environmental
Variation
The difference between individuals of the same species
Cell membrane
Controls what enters and leaves the cell
Nucleus
Contains DNA (chromosomes)
Cytoplasm
Where chemical reactions take place
Mitochondria
Respiration occurs here
Cloning
Genetically identical
How to clone a sheep
Adult sheep taken from sheep 1 that they want to clone
DNA extracted from cell
DNA placed into an embryo
Embryo implanted into a surrogate sheep - sheep 3
The enucleated egg cell and nucleus are then fused
Sheep 3 is then cloned
Embryo
Organisms that are genetically recessive to their parents
Difference between sexual and asexual reproduction
1 parent for asexual
2 needed for sexual
Selective breeding
When humans Breed organisms with specific genetic characteristics
Genetic engineering
Altering an organism’s genes to produce an organism with desired characteristics.
Advantages for genetic engineering
Genetic engineering is quick
Anyone can work on genetic engineering
Easily repeatable
Quicker than selective breeding
Disadvantages for genetic engineering
Higher risk of increasing allergies
Karge number of animals required
Environmental issues
Can be expensive
5 steps in breeding an organism
1 - decide which characterstic of species is most important
2 - select parents that show high levels of this chracteristic
3 - breed these individuals
4 - select the best offspring and breed again
5 - repeat for many generations
Advantages for selective breeding
Animals can be selected that cannot cause harm
New varieties may be economically important like producing more or better quality food
Disadvantages for selective breeding
Reduces variation within a species
Reducing number of genes by making organisms look more similar each generation
Chromosome
Strand/piece of DNA
What happens when a sperm fertilises an egg
Genes from the mother join with genes from the father
How do scientists predict what an organism’s offspring will look like
By carrying out a genetic cross
What do Punnett squares show
What happens to alleles in genetic cross
Genetically inherited disorder
Conditions passed from parents to their offspring in their genes
Examples of genetic disorders
Cystic, fibrosis, haemophilia, polydactyly
Cystic fibrosis
Produces lots of thicky sticky mucus that blocks air passages
Carrier
A person who has
1 copy of the dominant allele
1 copy of recessive allele
What does it mean if someone has a carrier
They carry a copy of the allele, but do not have the disorder
What do punnet spuares determine
The chance of a child inheriting a condition from their parents
Polydactyly
Disorder that results in a child being born with extra digits on their hands or feet
What do different types of dogs suffer from selective breeding
Labradors - suffer from hip problems
Pugs - suffer from breeding problems
Result of in-breeding
Pedigree dogs have lower life expectancy than crossbreeds
Why have organisms
Cotton
Corn
Bacteria
Been genetically engineered
What do they produce
Cotton - high yields
Corn - toxins that kill insects
Bacteria - medicinal drugs
When do organisms display characteristics of foreign genes
As the organisms develops
What do genetically engineered bacteria produce
Vaccines and antibiotics
Clone
An organism that is genetically identical to its parent and will look identical
Plants that reproduce asexually
Potato plants
Strawberry plants
Daffodils
Advantages of cloning
New plants produced quickly
Technique is cheap
All plants genetically identical so will have desired characteristics
Main disadvantage for cloning
increase risk of disease
2 animal cloning techniques
Cell cloning
scientists clone human cells in laboratory and use them for research into diseases
Beneficial uses of cloning for endangered animals
Endangered species could be cloned preventing their extinction
DNA
the molecule that carries genetic information for the development and functioning of an organism
DNA stand for
Deoxyribonucleic Acid
Genetic cross chromosomes are male XX and female XY
Parents genotype =
Parents phenotype =
Genotype XY XX
Phenotype Male x Female
XX - XY how genetic cross would look like
X X
__________________
| |
X | XX | XX
| |
Y | XY | XY
How would a gardener carry out selective breeding to ensure their roses produced large pink flowers
Parents with desired characteristics chosen
Bred together
Offspring with desired characteristics are bred together
Repeated for many generations
How is genetic information passed from a parent to a child
Genetic information is found in the nucleus of the sperm and the egg. When fertilisation occurs, this information is passed onto the offspring
How can insulin be made using geneticslly engineered bacteria
Genes that code for the production of insulin inserted into the bacteria
Bacteria now produce insulin
Bacteria multiply many times and produce large quantities of insulin
Bacteria then removed leaving behind the useful insulin
How is cutting a plant creating a clone
Can cut off part of a plant and then with that part you can grow another plant exactly like that (clone)
Name of DNA special structure
Double Helix
Where is DNA found in the cell
Nucleus
Arranged in chromosomes
Process genetic engineering
Locating an organism with a specific trait and extracting its DNA
Cloning a gene that controls the trait
Designing a gene to express in a specific wa
Transformation, inserting the gene into the cells of a crop plant
Cross the transgene into an elite background
What does GMO stand for
Genetically modified organism
What is a genetically modified organism
a plant, animal or microbe in which one or more changes have been made to the genome
Simple process of nuclear transfer cloning
After removing the oocyte nucleus, the donor cell nucleus is injected or fused with the enucleated oocytes before the reconstructed embryos are activated
Tissue culture
new skin and cartilage can be grown in a sterile environment
