Inheritance Flashcards
DNA
A molecule that contains
genetic information. DNA is stored in the nucleus of a plant or animal cell. It is passed on to offspring during reproduction.
Gene
A unit of genetic information
Genetic trait
A feature that can be passed
down by genes to the
next generation.
Inheritance
The survival of organisms
that are better adapted to
their environment.
Allele
The variation of the gene/ A version of a gene.
Homozygous
A genotype in which the alleles are the same, such as YY or yy.
Heterozygous
A genotype in which the alleles are different, such as Yy. When an individual has 2 different alleles.
Genotype
The set of genes carried by an organism that influence the appearance of its traits.
Phenotype
The set of observable traits in an organism.
Simple inheritance
When the appearance of an inherited trait is controlled by a single gene.
Dominant
A version of a gene that is expressed even when only one copy is present. The dominant allele is always symbolized by a capital letter.
Recessive
A version of a gene that is only expressed when two copies are present. The recessive allele is symbolized by the lower-case form of the same letter.
Punnett Square
A diagram used to determine the probability of offspring inheriting pairs of genes from their parents.
Fertilisation
The process by which male and female gametes are fused together, initiating the development of a new organism. The male gamete or ’sperm’, and the female gamete, ’egg’ or ’ovum’
Ovum (egg)
The egg cell, also known as the ovum, is the female reproductive cell. The egg cell is released from the ovaries in the female reproductive system. The egg cell is the female gamete responsible for reproduction in female organisms.
Sperm
The male reproductive cell. The sperm unites with (fertilizes) the ovum (egg) of a female to produce a new offspring.
Mendel
The principles of heredity. These principles form what is known as the system of particulate inheritance by units, or genes.
Variation
Variation in biology refers to any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).
Chromosomes
There are 23 pairs for chromosomes (so 46 altogether!) One chromosome of each pair comes from our mother and the other chromosome in each pair comes from our father! Egg and sperm cells are the only cells in the body to contain 23 chromosomes - they only have one copy of each pair. During fertilisation, these cells join together to form an embryo. This means the inside each cell of the embryo there are 46 chromosomes.
X Chromosome
This 23rd pair are the sex chromosomes, determining whether you are a boy or a girl. Girls have two identical X chromosomes, whereas boys have on X chromosome and a shorter Y chromosome.
Y Chromosome
This 23rd pair are the sex chromosomes, determining whether you are a boy or a girl. Girls have two identical X chromosomes, whereas boys have on X chromosome and a shorter Y chromosome.
