CB3 - Genetics Flashcards
What organisms can produce asexually?
Most insects
Many plants
What does asexual reproduction produce?
Genetically identical ‘clones’ offspring of the parent.
What are the advantages of sexual reproduction?
Creates variation, so there is a greater chance that offspring will be suited to new conditions.
What are the advantages of asexual reproduction?
Quicker
What are gametes?
Sex cells -
egg
sperm
What is formed when two gametes fuse during fertilisation?
Zygote
What does the zygote form?
A ball of cells using mitosis.
Where are the genetic instructions for an organism found?
DNA
What is a genome?
The entire genetic material of an organism.
What is the Human Genome Project?
A project dedicated to determining the base pairs that make up human DNA
What are genes?
Sections of DNA that contain a code for making protein.
How many ‘different’ chromosomes are there in a human body cell?
23
Is a human body cell diploid or haploid and why?
Diploid
Contains two sets of 23 unique chromosomes.
What is meiosis?
A type of cell division that results in the production of four haploid daughter cells.
What happens to a cell during meiosis?
The chromosomes replicate and their copies stay stuck to one another. There are now 4x 46 chromosomes.
The cells divide into two and then two again.
This leaves four haploid cells.
What is the structure of DNA?
Nucleus contains chromosomes.
A chromosome contains one long DNA molecule.
That DNA molecule is tightly coiled in proteins.
DNA is a double helix and polymer.
What are the four bases in DNA?
Adenine
Thymine
Cytosine
Guanine
Which bases form complementary base pairs?
A and T
C and G
What are the bases attached to?
A sugar attached to a phosphate group.
What is the grouping of a base, sugar and phosphate called?
Nucleotide
How are the bases held together?
The negatively charged part of one base attracts the positively charged part of another base, this forms hydrogen bonds.
Is DNA unique?
Yes, except for identical twins.
What is the experiment to extract DNA?
Mash the fruit to break down the cell wall
Mix together water, salt and washing-up liquid.
This breaks down the surface membrane and the membrane around the nucleus.
Filter the mixture and collect the filtrate.
Add protease to the filtrate to break down the proteins coiled around the DNA.
Add ethanol which forms a precipitate.
What are alleles?
Different forms of the same gene.
What is it called if both alleles for one gene are the same?
Homozygous
What is it called if the alleles for one gene are different?
Heterozygous
What is a recessive allele?
For that characteristic to be seen both alleles have to be ressisive.
What is a dominant allele?
For that characteristic to be seen one allele has to be dominant.
What is a genotype?
The alleles in an organism.
What is a phenotype?
What observable characteristics an organism has.
What are the male sex chromosomes?
XY
What are the female sex chromosomes?
XX
What are Punnett squares?
A way to demonstrate inheritance and work out the probability of offspring inheriting certain genotypes.
How do we show dominant and recessive genes?
Capital letter for dominant
Lower case letter for recessive
What are mutations?
A change in a gene that creates a new allele.
Errors in the genetic sequence
What is genetic variation?
Variation caused by the different alleles inherited during sexual reproduction.
Variation caused by mutations affecting the phenotype.
What is environmental variation?
Variation caused by surroundings.
E.g. - Plants height based off light and water.
What are acquired characteristics?
Characteristics that are changed by the environment during the life of an individual.
What is discontinuous variation?
Where data can only take a limited set of values.
What is continuous variation?
Where data can be any value in a range.
What are the three types of mutations?
Deletion
Insertion
Substitution
What is a deletion mutation?
When one base in the genetic sequence is deleted
What is a insertion mutation?
When one base is added to the genetic sequence
What is a substitution insertion?
When one of the bases in a genetic sequence changes
What is sickle cell mutation?
A mutation that changes the shape of the blood cell
What is cystic fibrosis?
A mutation that causes cysts to form in the lungs
