SB3 Flashcards
Genetics
What are the advantages of sexual reproduction
1- Produces genetically different offspring
2- Variation provides a survival advantage
What are disadvantages of sexual reproduction
1- It’s required for a species to find a mate
2- Takes a longer amount of time offspring to be produced
What are the advantages of asexual reproduction
1- only one parent needed
2- uses less energy and is faster
3- In favourable conditions offspring produce rapidly
What are the disadvantages of asexual reproduction
1- lack of variation therefore prone to disease
2- species are only suited to one environment
What is the role of meiotic cell division
Produces four genetically different daughter cells with haploid chromosomes
What is the structure of DNA
A polymer containing double-stranded helix linked by a series of complementary base pairs joined with weak hydrogen bonds
What are nucleotides made of
A deoxyribose sugar, phosphate and base.
What are the 4 organic bases and their complimentary pairing
A & T
C & G
What’s a genome
All the genetic information of a single organism
What’s a gene
A short section of DNA
What are the steps to extract DNA from fruit
- Mash fruit and mix into a beaker containing a solution of detergent and salt
2- Filter the mixture into a test tube
3- Add Ice-cold ethanol to filtrate
4- DNA will appear as a white precipitate
What is the use of detergent when gathering the DNA from fruit
It breaks down the cell membranes and nuclear membranes so the fruit cells can release their DNA
What is the use of salt when gathering the DNA from fruit
Causes the DNA to stick together so it’s more visible
What is the use of ice-cold ethanol when gathering the DNA from fruit
Causes the DNA to precipitate and therefore make it more visible
n/a
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What is protein-synthesis
Process of making a protein from DNA
What are the steps for transcription
1- Two strands of DNA helix are unzipped by helicase enzyme
2- RNA polymerase attaches to the DNA in a noncoding region just in front of the gene
3- RNA polymerase makes a complementary copy of the code where T base is replaced with U (mRNA)
4- mRNA leaves the nucleus to then attach to a ribosome
What are the steps for translation
1- Ribosome reads the code on mRNA as codons
2- Each codon codes for a specific amino acid
3- tRNA bind with their specific amino acid in cytoplasm (anticodons)
4- Anticodons bind with Codons creating a peptide bond
5- Process continues until a stop codon is reached
6- polypeptide chain forms to fold into a protein
How does genetic variants in the non-coding DNA of a gene affect a phenotype
RNA polymerase binds to non-coding DNA so a variant can affect the amount of RNA polymerase that can bind to it therefore affecting the final protein structure
How does genetic variants in the coding DNA of a gene affect a phenotype
Alters the sequence of bases therefore changing the sequence of amino acids and the activity of the protein
What was Gregor Mendel’s inheritance theory
Individuals inherit one allele from each parent which then are randomly to the next generation
How did Gregor Mendel demonstrate his inheritance theory through pea plants
He studied the inheritance of different characteristics in pea plants
1. When he bred green-pea plants with yellow pea plants, all the offspring produced yellow pea plants
2. When the yellow pea plants then self-fertilised some pea plants were green This was because the allele for green pea plants is recessive
dominant and the allele for yellow pea plants is dominant
Explain why there are differences in the inherited
characteristics as a result of alleles
Different combination of alleles within each person produces a different characteristic
What is a gamete
An organism’s reproductive cell
