Genetics Flashcards
(57 cards)
What is a chromosome made out of?
Very tightly wound coils of DNA and little balls of protein
They are found in the nucleus of eukaryotic cells
What is the polymer for the monomers:
- amino acids
- sugar
- nucleotide
Polymers:
- protein
- carbohydrates
- DNA
What is DNA?
- double helix shape made of two coiled strands (deoxyribose sugar)
- sugar phosphate backbone
- 4 base pairs joined together by weak hydrogen bonds
- nucleotide monomers (phosphate=circle, sugar=pentagon, base pair =rectangle)
What is an allele?
Alleles are different forms of the same gene
What is a zygote?
Something formed when two gametes ( sex cells ) fuse
What is a phenotype?
The characteristics that we see
What is a genotype?
The allele that makes up a given feature
What does homozygous mean?
An organism that has 2 alleles that are the same for a given feature
What does heterozygous mean?
An organism that has two different alleles for a given feature
What does dominant mean?
The allele shown in an organism’s feature
What does recessive mean?
An allele that has no effect if the dominant allele is present, two of these are required to display the recessive characteristic
What is a gene?
A section of a chromosome which controls a particular feature
What sex chromosomes do males and females have?
Male = X and Y Female = X and X
Which sex cell determines the sex of the offspring?
Male
What is a punnet square used for?
They are used to work out probabilities of different phenotypes caused by alleles
Why are males more susceptible to sex linked diseases?
As the Y chromosome is significantly smaller than the X and so carries fewer genes. Therefore they often only have one allele for sex-linked genes so that characteristic is shown even if it is recessive so it is more likely to be faulty
What does the shape of a protein determine?
What is does and how it works. E.g. the shape of haemoglobin allows it to carry more oxygen as it has a larger surface area.
What would happen of the DNA was copied incorrectly?
The amino acids would be wrong, so the protein shapes would be wrong, and there would be a small effect or maybe the phenotype might even change.
What is a mutation?
A mutation is the change in the sequence of bases on the genetic code which can have neutral, negative or beneficial effects.
What does a family pedigree chart show?
The probability of genotypes and phenotypes being passes from one generation to the next from parent cells
What is the Hayflick limit?
A cell normally divides only 50 times, but when cancer comes we don’t have this counter so the cell divides uncontrollably.
What are the two types of variation?
Continuous variation can have any value between two extremes (e.g. height)
Discontinuous/discrete variation consists of specific values with nothing between (e.g. blood groups)
What are the graphs for continuous and discrete variation?
Discrete - bar graph
Continuous - line graph
Why is there variation within a species?
- There is often genetic variation within a species due to mutations (small changes in the DNA of the organism)
- sexually reproduction leading to different allele which cause different phenotypes
- environmental factors that can influence variation meaning organisms acquire characteristics