inheritance, variation and evolution

Created by

evie wrennall

Cards (45)

allele
an alternative form of a particular gene
genotype
the combination of alleles for a particular gene
eg BB, Bb or bb
phenotype  
the physical expression of the genotype (the trait shown)
dominant  
an allele that only needs to be present once in order to be expressed
recessive
an allele that will only be expressed if there are two present
homozygous 
carrying two copies of the same allele for a gene
eg BB or bb
hetrozygous  
carrying two different alleles for a gene
eg Bb
monohybrid inheritance  
the pattern of inheritance shown when a characteristic is controlled by a single gene
polydactyly  
a genetic disorder caused by a dominant allele, where affected people have extra fingers or toes
cystic fibrosis  
a genetic condition that causes a build-up of muscle in the lungs
sex chromosomes  
the pair of chromosomes that determine the sex of organisms
asexual reproduction  
produces new individuals that are identical to their parents:
does not involve the fusion of gametes
gamete  
a specialised sex cell formed by meiosis
runners  
long shoots from plants, such as strawberries, that are used for asexual reproduction
meiosis 
cell division that forms two daughter cells with half the number of chromosomes of the parent cell
DNA 
nucleic acid molecules that contain genetic information and make up chromosomes
chromosomes  
long molecules found in the nucleus of all cells; which codes for a protein
genome  
all the genetic material found in an organism or a species
selective breeding  
the breeding process used by scientists and farmers to produce organisms that show the characteristics that are considered useful
genetic engineering  
the process of moving a gene from one organism to another
genetically modified (GM) 
organisms that have and specific areas of their genetic material changed using genetic engineering techniques
variation 
differences between individuals of the same species
evolution 
a gradual change in a group of organisms over a long period of time
natural selection  
the survival of individual organisms that are best adapted to their environment
fossils  
the remains of animals / plants preserved in rocks
binomial system  
the method of naming organisms by using their genus and species
genus
a group of closely related species
three-domain system  
a new classification system that divides organisms into three domains rather than five kingdoms
extinct  
describes a species that has died out
evolution 
the gradual change in the inherited characteristics of a population
Natural selection 
Put forward by Charles Darwin
All species have evolved from simple life forms that first developed more than three billion years ago
Darwin's observations 
Organisms often produce large numbers of offspring
Populations usually stay about the same size
Organisms are all slightly different- they show variation
Characteristics can be inherited
Darwin's conclusions 
1. There is a struggle for existence
2. More organisms are born than can survive
3. The ones that survive and breed are the ones better suited to the environment
4. They pass their characteristics to their offspring
5. Over long periods of time, the characteristics of population change
each gene may have different forms called alleles
an individual has two alleles for each gene.
the combination of alleles ina gene is called the genotype
how the alleles are expressed is called the phenotype
alleles can be dominant or recessive 
if two dominant alleles are present eg BB, the dominant characteristics is seen eg brown eyes
if two recessive alleles are present eg bb, the recessive characteristics is seen, eg blue eyes
if one of each allele is present eg Bb, the dominant characteristic is seen, eg brown eyes
only one pair out of the 23 pairs of chromosomes in the human body carries the genes that determine sex.
these are called sex chromosomes