Inheritance, variation and evolution Flashcards
allele
an alternative form of a gene
asexual reproduction
production of offspring from a single parent by mitosis, the offspring are clones of the parent
chromosome
structures that contain dna of an organism and are found in the nucleus
cystic fibrosis
a disorder of cell membranes caused by a recessive allele
dna
a polymer that is made up of two strand that form a double helix
dominant
an allele that is always expressed, even if only one copy is present
fertilisation
the fusion of male and female gametes
gamete
sperm and egg cell in animals; pollen and egg cell in plants
gene
small section of dna that codes for a specific protein
genome
entire genetic material of an organism
heterozygous
a genotype that have 2 different alleles - one recessive and one dominant
genotype
combination of alleles
homozygous
a genotype that has two of the same alleles, either two dominant or two recessive alleles
meiosis
the two stage process of cell division that reduce the chromosome number of the daughter cells, making gametes for sexual reproduction
mutation
change in dna
polydactyly
an allele that is only expressed if two copies of it are present
recessive
an allele that is only present of two copies of it are both present
sexual reproduction
production of offspring by combining the genetic information from gametes of two parent, leads to variation in the offspring
mitosis key points
- produces 2 IDENTICAL daughter cells
- the cell divides ONCE
- Chromosome number of the daughter cells is the same as the parent cells
- used for growth, repair and asexual reproduction
meiosis key points
- produces FOUR NOT GENETICALLY IDENTICAL daughter cells
- cell divides TWICE
- The chromosome number is reduced by half
- Produced gametes for sexual reproduction
Sex determination on females
females carry two X chromosomes
Sex determination on males
males carry one X and one Y chromosome
embryo screening
genetic test carried out on an embryo to see whether it carries a faulty allele
evolution
a change in the inherited characteristics of a population, over time, through a process of natural selection
evolutionary tree
a method used to show how scientists believe organisms are related
extinction
the permanent loss of all members of species
fossils
the remains of organisms from millions of years ago which are found in rocks
genetic engineering
the process by which scientists manipulate and change the genotype of an organisms
natural selection
process by which organisms that are better suited to an environment are more like to survive and reproduce
selective breeding
humans selecting animals or plant, that have a required characteristic, for breeding
speciation
process by which two species evolve from a single original species by natural selection. But these two populations are so different that they cannot interbreed and produce fertile offspring
variation
differences in characteristics of individuals in a population
why would a species evolve
- if a characteristic is advantageous in an environment, they will be able to compete better -
- meaning that they will be more likely to survive and produce offspring
- their offspring will inherit the advantageous allele
fossils could be…
- actual remains that have not decayed
- mineralised forms of the harder parts of an organism, such as bones
- traces of organisms such as footprints in mud
why do we have little evidence of early life forms
many organisms were soft bodied so left little trace
what do fossils do
help us understand how much or little organisms have changed as life developed on earth
how to carry out selective breeding
- choose parent with desired characteristic
- select offspring with best characteristic shown and breed to make next generation
- these offspring are then bred again and again, over many generation until desired result is achieved
how to remember classification by Linnaeus
Keep Ponds Cleans Or Fish Get Sick
how did linnaeus classify living things
kingdom, phylum, class, order, family, genus and species
variation may be due to difference in…
- the genes that have been inherited (nature)
- the conditions in which they have developed (nurture)
- combination (holistic)
how have organisms been named
by binomial system of genus and species
advantages of sexual reproduction
- produces variation in the offspring
- if the environment changes, variation gives a survival advantage
- natural selection can be increased
advantages of asexual reproduction
- only one parent needed
- more time and energy efficient as they do not need to find a mate
- faster
how can plants be cloned
- tissue culture
- cuttings
tissue culture method
- take out cells from a leaf
- place into petri dish
- place in correct conditions
- many sapling will grow
cuttings method
- propagation
what does the dna structure contains
- nucleotide
- phosphate
- sugar
- base
- double helix
