Biology Chapter 3 Chromosomes and Genes Flashcards
What is the genome
All the genetic material of an organism
What do chromosomes come in
Pairs
What is found on chromosomes
Genes
What are genes made up of
DNA
What shape is DNA
A Double Helix
What is the term for different forms of the same gene
Allele
eg blue eyes, green eyes, brown eyes
What type of allele is expressed even if only one of the pair is of this type
Dominant allele
What is the term used to describe the type of allele that must be present in both in order to be expressed - is written as a small letter
Recessive
What is the term used to describe having one dominant and one recessive allele e.g. Bb
Heterozygous
What is the term used to describe having both alleles the same eg bb or BB
Homozygous
What is the term used to describe the genetic makeup of an individual eg DD od Dd
Genotype
What is meant by the term phenotype
The features the person has because of their genotype
If both parents are heterozygous e.g Bb what will the offspring be
Both parents Bb
Gametes either B or b
Draw a genetic diagram (Punnet square) to show the result
B b
B BB Bb
b Bb bb
Genotype - 1BB, 2 Bb, 1bb
25% chance have recessive characteristic (bb)
50% heterozygous (Bb)
25% homozygous dominant (BB)
In a pedigree diagram what does it show
Shows link between different family members - you need to be able to read keys on a pedigree diagram and work out genotypes
What is a mutation
A random change in DNA or chromosomes
What is cancer
Uncontrolled cell division
What can cause skin cancer
UV light
Name 2 examples of genetic conditions
Down’s syndrome
Cystic Fibrosis
How would the chromosomes of a person with Downs syndrome be different
They have 47 chromosomes instead of 46
They have an extra chromosome on pair 21
What is genetic screening
A process used to see if a person is carrying a certain genetic condition
What is the name of the procedure used to check a foetal cells to see if the foetus has Downs syndrome
Amniocentesis
- risk of miscarriage with this procedure
What are the ethical concerns with amniocentesis
Person has to decide what to do with the results - do they keep the child or have an abortion
What is genetic engineering
Modification of DNA by inserting gene from another organism
Insulin is made by genetically engineered bacteria
What are the advantages of this
Can produce large amounts
Produces human insulin so is compatible to person (other animal insulin is slightly different)
Insulin is made by genetically engineered bacteria
What are the disadvantages of this
moral issue - some people think it is not right to alter organisms DNA
May be other unforseen outcomes from modification
what is the GM material getis into the wild?
