Inheritance, Variation and Evolution Flashcards
What’s DNA?
Chemical that all genetic material is made from and a polymer made of two strands
Where’s DNA found?
The nucleus of cells in chromosomes
What shape does DNA have?
Double helix
What’s a gene?
A small section of DNA
What’s the function of a gene?
It codes for a specific sequence of amino acids to make a specific protein.
What’s a genome?
An entire set of genetic material
What do scientists use understanding genomes for?
- Identify genes in genomes linked to diseases
- Know which genes are linked to inherited diseases
- Trace past human migration patterns
What’s DNA made of?
Nucleotides (sugar, phosphate group and a base)
What do the sugar and phosphate group form?
A backbone to DNA
What are the four different bases?
A, T, C, G
What are the pairs of the bases?
A pairs with T
C pairs with G
This is called complementary base pairing
What’s mRNA?
A messenger between DNA and ribosomes and its function is to copy the code from DNA.
What are some types of proteins?
Enzymes
Hormones
Structural Proteins
What’s a mutation?
A random change in an organism’s DNA.
What do mutations do?
Change the sequence of DNA bases
What are ways mutations can change
DNA?
Insertions - inserting a new base in the DNA sequence
Deletions - A random base deleted
Substitutions - A random base changing into another
What’s sexual reproduction?
When the genetic material from two organisms combine to produce offspring by meiosis
What gametes do animals have?
Female gametes: egg cell
Male gametes: sperm cell
How many chromosomes do each gamete have?
23
What gametes do plants have?
Female gametes: egg cell
Male gametes: pollen
What’s asexual reproduction?
Reproduction with one parent only by mitosis
What are offspring from asexual reproduction called?
Clones
What reproduces asexually?
Bacteria and some plants and animals
What’s meiosis?
A cell division that happens in reproductive organs to halve the number of chromosomes
What’s the process of meiosis?
The genetic information doubles.
The chromosomes line up in the centre and the cell divides.
Then the chromosomes live in the middle again and the cell divides, leaving four gametes with a single set of chromosomes
What happens after fertilisation?
The cell divides by mitosis severally to make multiple new cells and as the embryo develops, the cells will differentiate.
What are some advantages of sexual reproduction?
Offspring have a mixture of both sets of chromosomes, so variation.
Variation decreases chance of dying from change in environment
Variation means offspring are more likely to breed successfully (natural selection)
Can use selective breeding to speed up natural selection.
What are some advantages of asexual reproduction?
Offspring have a mixture of both sets of chromosomes, so variation.
Variation decreases chance of dying from change in environment
Variation means offspring are more likely to breed successfully (natural selection)
Can use selective breeding to speed up natural selection.
What are some advantages of asexual reproduction?
One parent
Less energy needed
Faster
Offspring can be produced in favourable conditions
What organisms can reproduce both sexually and asexually?
Mosquitoes, fungi and some plants
What does the XX and XY chromosomes mean?
XX: females
XY: males
What are alleles?
Different versions of the same gene
What’s phenotype and genotype?
Phenotype: physical characteristics
Genotype: the alleles an organism has
What does homozygous and heterozygous mean?
Homozygous: having two of the same alleles
Heterozygous: having two of the same alleles
What are dominant and recessive alleles?
Dominant: allele that always expresses itself
Recessive: allele that’s only expressed if there’s 2 copies
What’s cystic fibrosis?
A genetic disorder of the cell membranes that results in thick mucus in pancreas and air passages. and caused by a recessive allele.
What’s polydactyl?
Having extra fingers or toes and is caused by a dominant allele
What’s a person with a recessive allele of cystic fibrosis?
A carrier
What are some advantages and disadvantages of embryonic screening?
Advantages:
Treating disorders is expensive
It’ll stop people suffering
There are laws to prevent people taking it too far.
Disadvantages:
Implies people with genetic disorders are undesirable
Screening is expensive
Many people will use screening to pick the most ‘desirable’ baby
What did Mendel discover?
Characteristics in plants were passed down from one generation to another.
What are Mendel’s 3 conclusions about heredity in plants?
Characteristics are determined by heredity units
Heredity units are passed down to offspring
Heredity units can be dominant or recessive
What’s variation?
Difference in characteristics between individuals of the same species
What are the two types of variation?
Genetic and Environmental
What was Darwin’s theory?
Organisms had to compete for resources so the organisms with the most suitable characteristics would be more likely to survive and reproduce unlike the others so evolution occurred.
What’s natural selection?
a species changes over time in response to changes in the environment, or competition between organisms, in order for the species to survive.
What was Larmarck’s theory?
Any changes an organism acquired during its lifetime will be passed down to its offspring.
What’s selective breeding?
When humans breed animals and plants for certain characteristics
What’s the process of selective breeding?
- Select the ones with your desired characteristics
- Bread them together
- Select the best offspring and breed them together
- Continue the process many many times
What’s the problem with selective breeding?
Can cause inbreeding, which will cause health problems (diseases and defects)
What’s genetic engineering?
Transferring a gene for a desired characteristic from one organism’s genome to another organism’s
What’s the process of genetic engineering?
The desired gene is cut from an organism using enzymes
The gene is inserted in a vector which is then used to transfer the gene to the new organism (plasmid or virus)
What are the pros and cons of genetic engineering?
Pros:
Yield increase
GM crops can be modified to contain important nutrients missing in a country.
There have been no problems so far.
Cons:
Reduce farmland biodiversity
Possible risk to eating GM crops
Transplanted genes could get out into the environment.
What is cloning by tissue culture?
When some plant cells are put in a growth medium with hormones to grow into new plants
What’s cloning by cutting?
Taking a cutting from good plants and planting it to produce genetically identical copies
What are fossils?
Remains of organisms from millions of years ago, found in rocks
What are some ways fossils form?
Fossils are formed when:
• oxygen and warmth are absent so amber forms and the organism
• an organism is buried in clay
• hard parts of the organism are replaced by minerals as they decay
Why’s the fossil record incomplete?
Many didn’t become fossils
Many could’ve been destroyed by geological activity
Early life was soft bodied so decayed quickly.
What’s a species?
A group of similar organisms
What speciation?
The development of a new series
How does extinction occur?
New predators New diseases Catastrophic events Competitors Geological events
What are 3 ways to prevent antibiotic resistance?
doctors shouldn’t prescribe antibiotics if not necessary
patients should complete their full course
Restricting use