Genetics and Variation - Half Term 1 (9Aa, 9Ab, 9Ac) Flashcards
What is environmental variation?
Variation caused by an organism’s surroundings, including abiotic factors (e.g. temperature, light) and biotic factors (e.g. competition, predators)
Examples:
- piercings, clothing, weight
What is genetic variation? (Also known as inherited variation)
Variation caused by an organism’s genes, passed down from the parents
Examples:
- hair colour
- eye shape
- blood group
What is a species?
A group of living organisms that can interbreed and produce fertile young/offspring
The surroundings of an organism are called its _______________
Environment
What are characteristics?
Distinctive biological traits or features of the organism
What is the difference between an environmental factor and a physical environmental factor?
An environmental factor can be abiotic or biotic, but a physical environmental factor can only be abiotic
What is a resource?
A substance or object in the environment required by an organism for normal growth, maintenance and reproduction
What is the environment?
All living and non-living elements by which an organism is surrounded
What is an abiotic factor?
Non-living part of an ecosystem that shapes its environment
What is a biotic factor?
A living organism that shapes its environment
What is continuous variation?
A characteristic that changes gradually over a range of values (e.g. height)
What is discontinuous variation?
A characteristic that comes in groups rather than a range (e.g. blood group)
What is classification?
The process of arranging organisms into groups based on similar characteristics
How should discontinuous variation be shown in a graph?
- bar chart
- spaces in between the bars
- no ‘normal distribution’ curve
- group along x axis
How should continuous variation be shown in a graph?
- histogram
- no spaces in between the bars
- a ‘normal distribution curve’
What is a gamete?
It is a sex cell - sperm for males and eggs for females
How many chromosomes does an egg cell have?
23
How many chromosomes does a sperm cell have?
23
How many chromosomes does a zygote have?
46 in 23 pairs
How many chromosomes does an embryo have?
46 in 23 pairs
What does DNA stand for?
Deoxyribose Nucleic Acid
What shape does DNA take?
Coiled double helix (like a twisted ladder)
___________ come as identical homologous pairs (except sex chromosomes)
Chromosomes
How many pairs of chormosomes are there in humans
23, 46 total
What are genes?
Genes are sections of DNA/chromosomes, and they code for a specific characteristic. They are inherited from our parents and can come in different forms known as alleles
What is an allele?
Genes in different forms
A long strand of DNA is made up of combinations of ___ bases
4
What are the pairings of the bases in DNA?
(hint: AGTC)
Adenine - Thymine
Cytosine - Guanine
Where are chromosomes found?
Nucleus of a cell
True or False: One of each pair of choromosomes comes from each parent
True
There are different versions of each gene, one is often ________ over the others
Dominant
DNA is a _________ made from _________ joined together
monomer
polymers
DNA is a long chain (a)___________ that is made up of a combination of (b)____ DNA bases
a. molecule
b. four
What is the phosphate ion bonded to in a DNA molecule
Sugar
What is the sugar bonded to in a DNA molecule?
Base
What are the repeated units (monomers) of a DNA molecule named?
Nucleotides
What are the three components of a nucleotide?
- sugar
- phosphate group
- base (ATGC)
What is the name of the base beggining with A?
Adenine
What is the name of the base begining with T?
Thymine
What is the name of the base begginning with C?
CytosineW
What is the name of the base beginning with G?
Guanine
Draw a diagram of a nucleotide
(P)\
\
⬠Sugar (Deoxyribose) —- |Base|
What is a homozygous allele?
One in which the alleles are the same (e.g. aa, BB)
What is a heterozygous allele?
One in which the alleles are different (e.g. Aa, Bb)
Dominant alleles are shown using (capital/lowercase) letters
Capital (e.g. B for brown eyes)
Recessive alleles are shown using (capital/lowercase) letters
Lowercase (e.g. b for blue yees)
What is a genotype?
The genetic makeup of an organism (e.g. aa, Bb, CC)
What is a phenotype?
The physical expression or outcome of an allele pair (e.g. blue eyes)
What type of genotype is BB?
Homozygous dominant
What type of genotype is bb?
Homozygous recessive
What type of genotype is Bb?
Heterozygous
What joins the base to the sugar?
Nitrogen atom
What types of bonds are there between the nucelotides?
Covalent
How are the two nucelotide chains held together?
Hydrogen bonds
