Question | Answer |
Adenine | A base that is found in DNA. Adenine (A) will only bond with Thymine (T) and this pairing forms part of the 'rungs' of DNA. |
Allele | One of a number of possible forms of a gene. Each characteristic has two alleles. |
Amino Acid | Building blocks of proteins - there are 20 different kinds. |
Asexual reproduction | Reproduction of identical offspring from a single parent. No gametes are involved (e.g. fission, spores) |
Autosomes | Any chromosomes found in a cell other than the sex chromosomes. |
Base | One of four chemicals which make up the 'rungs' of DNA: either A-T or C-G. |
Biodiversity | The variation in species within an ecosystem. |
Cell | The structural and functional unit of all living organisms. |
cell division | The formation of two or more daughter cells from one original cell. |
chromosome | Thread-like structures bearing genes that are found in the nucleus of a cell. Visible during the prophase of cell division. |
characteristic | A distinctive inherited feature of an organism. |
cloning | A process that produces identical genetic individuals. |
cytosine | A base that is found in DNA. Cytosine (C) will only bond with Guanine (G) and this pairing forms part of the 'rungs' of DNA. |
DNA | Deoxyribonucleic acid. A molecule found in the nucleus of cells which codes for an individual's genetic makeup. |
DNA replication | The process whereby DNA makes an exact copy of itself. |
dominant | An allele that controls the phenotype regardless of what the other allele is. |
double helix | A term used to describe the structure of DNA; a spiral-ladder shaped molecule. |
enzymes | Are proteins that act as biological catalyst in living organisms. They control the rate of reactions. |
fertilisation | The fusion (joining) of a male and a female gamete to form a zygote. |
gamete | A sex cell: Ovum and sperm in animals or ovule and pollen grain in plants. A cell that has to join with another gamete to form a zygote before further development can occur. |
gene | A length of DNA carrying the code for one feature. |
genetics | The study of how living organisms inherit features from one generation to another. |
genetic code | The genetic information held in DNA. |
genetic diversity | The variation in the genetic code within a species, population, ecosystem. |
genotype | The combination of two alleles that an organism has for a particular gene. |
guanine | A base that is found in DNA. Guanine (G) will only bond with Cytosine (C) and this pairing forms part of the 'rungs' of DNA. |
heterozygous | Having two different alleles for a particular gene; not true breeding. |
homozygous | Having two identical alleles for a particular gene; breed true when crossed with genetically identical organisms. |
inheritance | The passing on of traits from generation to generation through the genetic code. |
karyotype | Photograph of individual chromosomes of a cell arranged in pairs and showing their number, size and shape. |
meiosis | The type of cell division which produces sex cells/gametes (sperm and eggs/pollen and ova). In animals it occurs in the ovaries and testes. A process in which a diploid nucleus divides twice to produce four haploid, genetically different nuclei. |
mitosis | The type of cell division which produces two identical daughter cells from one parent cell. |
molecule | Two or more atoms chemically bonded together, e.g. CO(2) or O(2). |
mutation | A change in the sequence of bases in the genetic code which is transmitted to the subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes. |
nucleotide | A molecule containing a sugar-phosphate-base, found in DNA. Nucleotide bases pair to form DNA. |
offspring | New individuals formed by either asexual or sexual reproduction. |
organism | An individual that is able to grow and reproduce, etc. (MRS C GREN) |
ovaries | The female organ that produces female gametes - eggs. Eggs are used in sexual reproduction in both plants and animals. |
pedigree chart | A chart which shows how genes are inherited. |
phenotype | The characteristics of an organism produced by a particular genotype. |
proteins | Molecules that contain amino acids. They are found in all living organisms. There are many different types and all have important roles in living systems. |
Pollen | The male gametes in plants |
Punnet Square | A diagram used to predict the phenotype and genotype ratios of offspring by showing how alleles combine together during fertilisation. |
pure breeding | Organisms homozygous for a trait |
recessive | An allele which is only expressed in the offspring if the dominant allele is absent. |
selective breeding | A process that is used to breed for specific required traits. |
semi-conservative replication | DNA replication by 'unzipping' a DNA molecule followed by pairing up of nucleotides to produce two new DNA molecules each with one original and one newly synthesised strand of DNA. |
sex chromosome | A chromosome that determines the sex of the individual. |
sexual reproduction | Form of reproduction involving the fusion of two gametes from two parents. Produces a variation in the offspring. |
testes | The male organ that produces male gametes - sperm. Sperm are used in sexual reproduction in animals. |
thymine | A base that is found in DNA. Thymine (T) will only bond with Adenine (A) and this pairing forms part of the 'rungs' of DNA. |
trait | A feature whose appearance is determined by genes. |
triplet | A sequence of three nucleotides found on a DNA strand. Codes for a protein. |
variation | The differences between individuals. |
zygote | A fertilised egg. A single cell containing chromosomes from male and female gametes at the time/point of fertilisation. |
anther | Found in plant flowers and carries pollen - the male gametes of plants. |
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