Biology Terms: Year 11
Genetics
Independent
Assortment (occurs
during meiosis)
When homologous chromosomes line up in the middle of the cell in no particular order
so that each egg or sperm has a different combination of alleles from each parent
What the organism looks like eg blue eye
Phenotype
What genes(alleles) the organism has eg BB, Bb or bb
Genotype
Meiosis
Crossing over
(occurs during
meiosis during
gamete formation)
Autosomes
Purebreeding
Dominant
A type of cell division which produces 4 gametes (egg and sperm cells) with half the
number of chromosomes. It occurs in the reproductive organs and each gamete has a
different combination of alleles.
When homologous pairs of chromosomes (one from each parent) match up and parts of
the chromosomes overlap, break off and rejoin with the other chromosome. This
exchanges alleles so that the eggs or sperm have a mixture of alleles from each
parent in them
Body chromosomes of which we have 44
offspring that are the result of mating between genetically similar kinds of parents.
Pure bred animals have homozygous alleles eg BB or bb
an allele that masks the presence of a recessive allele in the phenotype. We use capital
letters to represent dominant alleles. Eg BB, Bb
Cloning
This process makes organisms which are genetically identical.
Gamete
a sex cell (egg or sperm)
Characteristic
A feature of an organism
Variation
Non –inheritable
mutations
heterozygous
Asexual
reproduction
Natural selection
DNA
Genetic code
Semi-conservation
replication
The natural differences that occur between organisms
When mutations occur in DNA that is not in the eggs or sperm so cannot be passed
on to the offspring
When there are two different alleles eg. Bb
A form of reproduction when offspring are produced from one parent and no eggs or
sprem are involved
When an environmental change causes organisms that have an advantage, to survive
better and produce more offspring eg peppered moth
Deoxyribose nucleic acid. It is a double stranded molecule found in the nucleus of
cells which carries the genetic information for the organism.
The order of the bases along the DNA molecule which determines which proteins will
be made by the cell
When the new piece of DNA that is made has one new strand and one from the
original strand
Zygote
Allele
Recessive
Mitosis
Chromosome
Homologous chromosomes
Sex chromsomes
Pedigree chart
Gene
Testcross(backcross)
Homozygous
Fertilisation
mutation
Inheritable mutations
Sexual reproduction
Inheritance
evolution
Nucleotide
a cell that is formed when a sperm and an ovum combine their
chromosomes at conception. A zygote contains the full
complement of chromosomes (in humans 46) and has the potential
of developing into an entire organism.
A different form of a particular gene eg. A recessive form or a
dominant form
an allele that is masked in the phenotype by the presence of a
dominant allele. Recessive alleles are only expressed in the
phenotype when the genotype is homozygous recessive (bb).
A type of cell division which produces two identical daughter
cells with the same number of chromosomes as the parent
cell.
It is for growth and repair of cells
A strand of coiled up DNA. There are 46 in our body cells and
23 in egg and sperm cells
The pairs of chromosomes in a cell (one from mother and one
from father)
The X and Y chromosomes. Females have 2 X’s (XX) and males
have Xand Y (XY)
a branching tree diagram that shows traits being passed
through a family
A small piece of the DNA which has the code(information) to
produce a particular characteristic
When a homozygous recessive organism is mated with another
organism to find out if the other organism is homozygous or
heterozygous for a characteristic
2 of the same alleles eg bb or BB
When an egg and sperm join together
A change in the genetic code (the order of the bases in the
DNA) which creates whole new alleles
When mutations occur in DNA in the eggs or sperm so can be
passed on to the offspring
The form of reproduction that involves the joining of an egg and
sperm to produce offspring. It requires 2 parents.
The passing on of traits from one generation to the next
generation.
When there is a change in the species over a period of time
The building blocks of DNA containing sugar molecule
(deoxyribose) a phosphate molecule and one of 4 bases
(adenine,thymine,guanine, cytosine)
DNA replication
Bases
The process whereby DNA makes an exact copy of itself
before the cell divides so there is enough DNA for the new cell
Chemicals that make up the ‘rungs’ of the DNA double helix.
Cytosine always pairs with Guanine, Adenine always pairs with
Thymine