Topic 6 Inheritance , Evolution Flashcards
Features of sexual reproduction
-Generic variation-able to adapt during environmental changes to survive (natural selection)
-Requires 2 parent gametes
-Can be exploited by humans in selective breeding to improve yield
-Involves 2 gametes fusing in fertilisation
Features of asexual reproduction
-Only 1 parent cell
-Quicker and more time efficient as no need to find a mate
-Can reproduce very quickly during times of ideal conditions
-No genetic variation so survival is difficult during changes in conditions
Examples of species which undergo sexual and asexual reproduction
-Malarial parasites reproduce asexually in the human host and sexually in tbe mosquito vector
-Fungi reproduces asexually in pores and sexually for genetic variation
-Some plants reproduce asexually to produce seeds and sexually through runners like strawberry plants and bulb division in daffodils
What is a genome?
All of the genetic information making up an organism
Uses of genomes in studying
-Understanding and treatment for genetic disorders
-Search for genes linked to different types of disease
-Tracing human migration patterns-ethnic background
What is a gene?
A section of DNA that codes for a specific sequence of amino acids and so a specific protein
What is DNA and where is it located?
A polymer made up of 2 stands making up a double helix
Stored in chromosomes in the nucleus of cells
What’s makes meiosis different to mitosis?
Meiosis is when DNA is replicated, then the cells divide twice into 4 gametes each with a single set of chromosomes.Therefore each gamete is genetically different.
Whereas mitosis results in genetically identical offspring
What is meiosis and where does it happen
Type of cell division needed to produce gametes.
Happens in reproductive organs such as testes and ovaries
What is fertilisation?
The fusion of gametes to restore the original number of chromosomes.The new cell divides by mitosis to increase the number of chromosomes and an embryo is developed which can differentiate.
After meiosis, the number of chromosomes halves from 46 to 23.
What are the 4 bases and pairings?
Thymine,Adenine,Guanine,Cytosine
AT GC
What is the structure of DNA?
What’s a nucleotide?
How does the structure if DNA impact the protein made?
How many bases code for an amino acid?
A polymer made of 4 different nucleotides
Consists of a common sugar and phosphate and a a base attached to the sugar
The order of the bases controlles the order of the amino acid sequence which code for a specific protein
3
What is an allele?
Genotype
Phenotype
Heterozygous
Homozygous
Dominant allele
Recessive allele
Allele is a version of a gene
Genotype is the alleles of a persons gene
Phenotype is the allele expressed
Heterozygous is having 2 different alleles for the same gene(trait)
Homozygous is having the same 2 alleles for a specific gene(trait)
What is cystic fibrosis?
An inherited disorder of the cell membrane.Caused by having the recessive allele.
A person with one defective and one normal allele is a carrier but doesn’t have cystic fibrosis as the normal allele is dominant
What’s polydactyly?
An inherited disorder resulting in someone more extra fingers or toes.
Caused by a dominant allele.There are no carriers because if you have the defective allele is it expressed as a phenotype because it is dominant
What is embryo screening and what are objections to it?
When embryos are tested in a lab to see if they’re defective or healthy, healthy embryos are implanted into the woman
It is expensive and the money could be spent elsewhere in the health service, lots of embryos are created but only a few are used meaning many are destroyed- unethical
Scientists can create embryos with desirable features-unethical
How many pairs of chromosomes control only human characteristics?
22 pairs
Describe the protein synthesis
Transcription:The base triplet sequence of the gene is copied to make a complementary template ( a single stand) called mRNA in the nucleus.
Translation:The mRNA moves into the cytoplasm and attaches to a ribosome. An tRNA bring amino acids to the ribosome, the ribosome reads the triplets of bases on the mRNA.Ribosome joins together the correct amino acids in the correct order. The correct sequence of amino acids creates the complete protein chain, protein chain folds into a unique shape
How many nucleotides code for one protein?
What does the order of amino acids determine?
3
Shape and function of the protein
Why can mutations alter the protein shape and function?
A few mutations can code for an altered protein, meaning the active site has changed so the substrate no longer fits the enzyme. Or structural proteins such as collagen lose their strength
What can a mutation do?
In terms of bases
Change a single or a few bases, most do not alter the protein but mutations happen continuously
What is selective breeding?
Reasons for selective breeding?
Negatives of selective breeding?
1.When humans breed plants or animals together for particular genetic characteristics.
2.Disease resistant crops, domestic dogs with gentle nature, animals that produce more meat and milk, large or unusual flowers
3.Can involve inbreeding which leads to offspring with genetic diseases/defects and reduces genetic diversity
Process of selective breeding?
Desired characteristics are identified, parents with these characteristics or similar and bred together. The offspring with desired characteristics are bred together, this is repeated until all offspring has desired characteristics
1.What can variation be due to?
2.What is a species?
1.Genetics, environment, both
2.Organisms with similar characteristics that are capable of breeding to produce fertile offspring
