B6 Flashcards
sexual reproduction
the fusion of male and female gametes
asexual reproduction
involves only one parent with no fusion of gametes
meiosis
cell division which produces 4 daughter cells each with half the normal number of chromosomes, forming gametes
mitosis
cell division which produces 2 daughter cells each with the same number of chromosomes, for growth and repair of tissues and for asexual reproduction
DNA
A polymer made up of 2 strands, forming a double-helix, contained in chromosomes carrying the genetic information for an organism
Non coding DNA
Parts of DNA which are not genes but may switch genes on and off and so can still be affected by mutations
Nucleotide
Sugar + phosphate + base- monomer that makes up DNA
Base
4 molecules A/ T/ C/ G which are use to write the DNA code
Protein Synthesis
Process of using the DNA code to order amino acids and build proteins
Triplet Code
Each amino acids is coded for by 3 bases eg CCG or AAT etc
Mutation
A random change in the DNA (could be harmful, harmless or beneficial)
Gene
A small section of DNA on a chromosome which codes for a protein
Chromosome
Long piece of DNA , containing many genes
46
Number of chromosomes (in 23 pairs) in a human body cell
23
Number of chromosomes in a human sex cell
Genome
The entire set of genetic material of an organism
Gametes
Sex cells, such as egg and sperm cells
Allele
Different versions of a gene eg blue eyes/ brown eyes
dominant
A gene that is expressed in the phenotype when at least one allele is present
heterozygous
Alleles present are different
homozygous
Alleles present are the same
genotype
alleles that are present
phenotype
physical characteristics/features produced by the alleles
cystic fibrosis
A disorder of cell membranes where mucus is thick and sticky
polydactyly
Inherited disorder where the individual has extra digits (fingers or toes)
sex chromosome
Female XX Male XY ( in humans)
tissue culture
Method of cloning using small groups of cells from part of a plant to grow identical new plants
cuttings
A simple method used by gardeners to produce many identical new plants from a parent plant
embryo transplant
Method of cloning. Splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers
adult cell cloning
Nucleus is placed into empty egg cell, electric stimulus to start
embryo development then put into the womb of an adult female
variation
Differences in the characteristics of individuals in a population
evolution
A change in the inherited characteristics of a population over time through the process of natural selection
Variation / Advantage/ Natural selection/ Evolution VANE
natural selection
A process which gives rise to phenotypes best suited to their environment because non suited organisms die out
species
A group of animals that can interbreed and produce fertile offspring
speciation
Formation of a new species through natural selection from an isolated population eg by geography on an island
Selective breeding
The process by which humans choose the parents and breed plants and animals for particular genetic characteristics