Inheritance, Variation and Evolution Flashcards
What organisms reproduce asexually?
Bacteria, fungi, small plants and animals
What are the advantages of sexual reproduction?
- Variation
- If there’s a change in environment, natural selection can happen
- Natural selection can be sped up by humans in breeding to increase food production
What are the advantages of asexual reproduction?
- Only one parent needed
- Quicker
- A mate doesn’t need to be found
- Many identical offspring can be produced
What are the functions of mitosis?
Growth, repair and asexual reproduction
What is the process of meiosis?
1) The chromosomes duplicate
2) The cell divides into two
3) Each cell divides again
Each cell will have 23 chromosomes
What is the purpose of meiosis?
To produce gametes
What is a diploid?
A cell that has 46 chromosomes
What is a haploid?
A cell that has 23 chromosomes
What does a nucleotide consist of?
A base, phosphate group and sugar
What is a triplet / codon?
A three base sequence that codes for a specific amino acid
What is the process of protein synthesis?
1) The base sequence of the gene is copied into the mRNA in the nucleus
2) The mRNA passes into the cytoplasm and then attaches onto a ribosome
3) Amino acids are brought to the ribosomes on carrier proteins
4) The ribosome reads the triplets of bases in the mRNA and uses this code to put together the amino acids in the correct order
5) When the protein chain is complete, it’s folded into a specific shape to carry out a specific function
What is a mutation?
A random change to the base sequence of a gene
What are the chances of mutation increased by?
Smoking and radiation
What is an insertion mutation?
When a new base is inserted into the DNA sequence which has a knock on effect in the chain and changes the amino acid
What is a deletion mutation?
When a random base is deleted from the DNA sequence, having a knock on effect in the chain and changing the amino acid
What is a substitution mutation?
When a random base in a DNA sequence is changed to a different base- this doesn’t have a knock on effect
What does coding DNA do?
Determines the structure of the proteins coded for
What does non coding DNA do?
Switches genes on and off to control whether the protein is made or not
What did Gregor Mendel do?
He discovered the existence of dominant and recessive alleles
What is Darwin’s theory of natural selection?
Due to mutations, there’s variation in a population and some individuals are better suited to their environment. They are therefore more likely to survive and pass on their advantageous genes
What was Lamark’s theory of evolution?
The changes an organism aquires during its lifetime would be passed onto it’s offspring
e.g. a giraffe that stretched its neck often to reach food would have offspring with longer necks
How are fossils formed from preservation?
They are preserved in places where no decay happens
What is decay?
The breakdown of dead matter
What affects the rate of decay?
Temperature, pH levels, water and oxygen
How are fossils formed by gradual replacement by minerals?
The organism dies and falls into soft mud or silt which turns into rock, encasing the body. Over millions of years, the hard parts of the body are replaced by minerals while the soft parts decompose
How are fossils formed from casts and impressions?
When an organism is buried in a soft material like clay, the clay hardens around it and when the organism decays, a cast is left
What is a species?
A group of organisms with similar characteristics that can breed with each other to produce fertile offspring
What is Alfred Russel Wallace best known for?
His work on the theory of speciation
What is speciation?
The formation of a new species
What is the process of speciation?
1) The population becomes isolated by some sort of barrier, e.g. a river meaning that they can no longer breed with each other
2) Different characteristics will develop over time across the separated population due to mutations
3) Due to natural selection, eventually the separated population will become two different species due to the different environments and different variations being better adapted for them
4) Now they can no longer breed because they are two different species
How do antibiotics affect bacteria cells?
1) The bacteria cell wall gets broken down by the antibiotic
2) Water enters the cell by osmosis
3) The damaged cell wall cannot withstand the pressure of the water and the cell bursts
How does antibiotic resistance develop?
1) Some bacteria in a population mutate, making them resistant to an antibiotic
2) This can be caused by an overuse of antibiotics which makes an increased chance of mutations
3) The non resistant bacteria are destroyed by the antibiotic
4) This means there is now reduced competition of the nutrients for the resistant bacteria that survived
5) They now reproduce by binary fission, making a whole population of resistant bacteria
6) Now if the antibiotics are taken again, nothing would happen
Define extinction
When all the members of a species dies out
What is an endangered species?
A species that is close to extinction
What can cause extinction?
Changes to the environment e.g. climate change, new predators e.g. the dodo and humans, new diseases or new species competing for food and territory
Define mass extinction
The extinction of many species within a short space of time
What did Carl Linnaeus develop?
The class system of organisms
What is the order of the class system, starting with the largest
Kingdom, phylum, class, order, family, genus, species
What is the binomial name of an organism?
The genus name combined with the species name e.g. panthea leo - lion
What did Carl Woese propose?
The three domain system, where organisms are grouped into three large groups called domains: archea, bacteria and eukaryotes
What is selective breeding?
When organisms are chosen for desirable genetic characteristics and bred so that their offspring inherit those characteristics
What is the process of selective breeding?
1) Parents with desired characteristics are chosen
2) The parents are bred together
3) Those offspring with desired characteristics are bred together
4) This continues over many generations until all of the offspring show the desired characteristic
Why can inbreeding lead to an increased risk of genetically inherited disorders?
Because most genetic disorders are caused by a recessive gene
What does genetic engineering involve?
Taking a gene from one organism and inserting it into the genome of another organism
What is the process of genetic engineering?
1) The useful gene is cut from an organisms genome using enzymes and inserted into a vector
2) The vector is a bacterial plasmid or a virus
3) The vector is then inserted into the target cells, which will begin producing the protein that the gene codes for
What is the process for genetic engineering helping the mass production of insulin?
1) Healthy cell extracted
2) Enzymes cut out insulin gene
3) Plasmid extracted from a bacteria and cut open with enzymes
4) Insulin gene inserted into plasmid
5) Plasmid put back into bacteria
6) Bacteria can now produce insulin and reproduce
7) Culture of bacteria is grown at optimum conditions and insulin extracted
What is a genome?
The sum of all a person’s genetic information
What are the benefits of genetic engineering?
- Desired characteristic chosen will be increased in the population
- Could be used to increase crop yields
- Could be used to engineer crops to contain nutrients that are lacking in developing countries
- Could make crops resistant to specific diseases
What are the concerns of genetic engineering?
- Could affect the number of wild flowers that live in and around the crops (reducing biodiversity)
- We don’t understand the long term effects of eating genetically modified crops
- The transplanted gene may get out into the natural environment
How can you clone a plant with a tissue culture?
The plant cells are put in a growth medium containing nutrients and auxin and they will grow into clones of the parent plant
How can you clone a plant with cuttings?
Cuttings from the parents plant are taken and planted and a clone of the parent plant will grow
How can you produce animal clones with an embryo transplant?
1) Sperm and egg are used artificially to create an embryo
2) The embryo develops and is split many times to form multiple clones embryos
3) These cloned embryos are implanted into different surrogates
4) The offspring will all be clones of each other
How was dolly the sheep made from adult cell cloning?
1) An egg cell was taken from sheep A and the nucleus was removed and destroyed
2) A body cell was taken from sheep B and the nucleus from this cell was removed and put in the empty egg cell from sheep A
3) This cell was stimulated with an electric shock to become an embryo
4) The embryo was placed in a surrogate sheep
5) When dolly was born she was a clone of sheep B
