Topic 3 Using Spec Flashcards
What are the advantages of asexual reproduction
Lots of identical offspring
Faster
No mate
In terms of speed why is asexual reproduction an advantage
As the reproduction is faster than sexual reproduction
In terms of mating why is asexual reproduction an advantage
No mate is required therefore asexual reproduction is more efficient in regards to time and energy
Why is lots of identical offsprings an advantage of asexual reproduction
As if conditions are favourable, producing lots of identical offspring is positive
What is a disadvantage of asexual reproduction
As there are identical offsprings there isn’t a lot of variation in the population
What are the advantages of sexual reproduction
Variation in offspring
Artificial selection
In terms of variation of offspring , where is this an advantage to sexual repeat
As the offsprings aren’t identical the chances of population being able to survive environment change by natural selection increases as some individuals are likely to be adapted to the new conditions
Why is mating a disadvantage within sexual reproduction
As it requires time and energy to find a mate to produce and offspring
Explain the role of meotic cell division including chromosome info
Step 1
Cells split - each cell has pair of each chromosome (diploid cell)
During Melissa each pair of chromosome replicate and the cell splits in two
Step 2 of meotic division
There are now two identical cells
The diploid cell divides again
Step 3 of meotic division
4 genetically different gametes that have half the number of chromosomes of the parent cell are created
Cells that have 1 copy of each chromosome are haploid cells
Step 4
The gametes then fertilise
Describe the dna structure in terms of polymers
Double helix polymer
Two strands coiled together to form the double helix
The strands are linked by complimentary base pairs - adenine thymine and cytosine guanine
They are held together by weak hydrogen bonds
What is a gene
A small section of dna which codes for a sequence of amino acids, which then combine to give a specific protein
What is a nucleotide
consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base.
What are the three components nucleotides are made up of
A sugar
A phosphate
A base attached to the sugar
How can dna be extracted from fruit
1) Grind a sample of fruit (such as strawberry) in soapy water to break open the cells which releases the dna
2) filter the sample to produce a filtrate
3) Very slowly, pour ice-cold ethanol into the filtrate.The DNA moves into the ethanol by precipitation, and can then be removed with a wire loop.
how does the order of bases in a section of DNA decides the order of amino acids in the protein and that these fold to produce specifically shaped proteins such as enzymes
Order of bases on dna tells us the order for combining amino acids to create certain proteins
Can change the protein made by a gene by altering the sequence of bases in the gene
This is because the order of amino acids changes how a protein folds together, which affects its structure and function.
What two stages does protein synthesis happen in
Transpiration and translation
What happens in transcription
Double stranded dna is unzipped and one strand is used to make a templates of dna code in form of mRNA
Enzyme rna polymerase joins mRNA template
mRNA template leaves nucleus
What happens in translation
mRNA template used to guide protein synthesis on ribosomes located in the cytoplasm
Specific amino acids are delivered by tRNA to add to the forming protein change
What is a phenotype
Set of observable characteristics of an individual
Describe the work of Mendel in discovering the basis of genetics
Preformed breeding experiments on pea plants - showed characteristics were determined by inherited units
What happened in the 20th century with mendels work
The similarity between the behaviour of chromosomes and Mendel’s ‘units’ was recognised.
Consequently, it was decided that the ‘units’ were located on chromosomes.
Additionally, the ‘units’ were renamed genes.
What is an allele
Different forms of the same gene
What is the dominant allele
Represented by a capital letter eg B (brown eyes)
If someone has a copy of B allele they will have brown eyes no matter what other allele is present
What is a recessive allele
Has to have two copies of allele eg bb
if b was blue eyes
A person can only have blue eyes if both of their alleles are b.
What is a genotype
Combination of alleles an organism has
When is a heterozygous?
if two alleles are different eg Bb
When is a person homozygous?
If the two alleles ade the same eg BB or bb
What is monohybrid inheritance
inheritance of traits determined by a single gene.
What colour could pea plants be
Green or yellow
What is the probability (%) of recessive phenotype in the offspring of parents with genes Gg and Gg?
25%
How many pairs of chromosomes are responsible for determine sex
1 they are called X amd Y
What letters are males
XY
What letter are females
XX
