revision sheet heredity Flashcards
outline mitosis
- IPMAT
- Interphase is the growth phase and dna replication phase
- Prophase spindle fibers start to form at eaither end of the poles the chromosomes become visible
- Metaphase the chromosome line up along the equator single file
- Anaphase spindle fibers attache to centromeres and begin to pull them to either poles
- Telophase 2 nuclear membranes form
- Cytokinesis the division of the cytoplasm to create 2 new cells
outline binary fission
- DNA replication where each copy attatches to a part of the cell membrane then 2 sides of the cell begin to pull apart creating a cleavage then they divide into two separate cells
outline meiosis
- IPMAT IPMAT2
- The process of a single cell dividing twice to produce 4 daughter cells
- Due to meiosis being with games thers twice as many chromosome to begin (diploid 46) then during 2 division phase turns into a haploid 23
outline what fertilisation is
- is the process of sperm and ovum fusing together to create a zygote
draw and label the structure of a chromosome
centromere, chromotids, genes
where can dna be found
in the nucleus and in some mitochondria
what are the 2 steps in making a protein
trascription and translation
decribe transcription
TRANSCRIPTION
- A small section of DNA is undipped exposing nucleotide bases
- This then bgins by binding to a spromoter sequence then
RNA polyermase runs along finding spare nucleotides to make a complimantary strand.
- Once the enzyme reaches a terminator sequence it stops and dicconnects
- the mRNA sequence gets packed with a ploy a tail on the end to protect the sequence and a methalyated cap which acts as a signaling molecule to be recognised by ribosome, slicing also takes place where introns are spliced out joining extrons together
describe translation
- mRNA leaves the nucleus goes through the cytoplasm and attatches to ribosome via the methalyated cap
- mRNA is then read by ribosome with tRNA having a sequence of three nucleotides called an anticodon, which can bind to specific mRNA codons. the tRNA carries the amino acid specified by the codons.
- The amino acids then all connect creating a polypeptide chain
- Once the stop codon is reached the peptide is then folded into a protein
- Describe examples where the environment can have an effect on the phenotypic expression of the organism.
- Hydrangeas phenotype can be expressed differently due to the different soil types
- Alkali soil flower petals are pink
- Acidic soil flower petals are purple
- Describe the different types of mutation that can occur during cell division.
Point mutation – is a change in DNA where only one nucleotide is altered
- Substitution
- Insertion/deletion
Chromosomal mutation- this is when mutations occur at a larger scale when chromosomes get tangled and can damage others
- Deletion- parts being removed then other seconts joining together
- Inversion- broken and turns upsidedown before repairing itself
- Duplication -inserting a section of the chromosome that already exists
- Translocation breaks off and attaches to another separate chromosome.
- Briefly describe the possible impacts of a point mutation on the protein produced.
Point mutation is a much lower scale mutation as its is where the DNA is changed and only one nucleotide is altered. This means in a different amino acid produced a changeg to the termination codon or creates a new sequence.
- Describe the role of crossing over in creating variation within a population.
This is the exchange of alleles on homologous chromosomes to create unique combination. This giving the offspring new generic traits of their own therefore increasing variation within the population.
- Describe the role of random assortment of chromosomes in creating variation within a population.
This process occurs in meisis phase 1 when homologus chromosomes spread to each pole creating different combinations due to having different orientation the daughter cell the receiving unique combiantions of chromosomes those which are different from the parents.
- Describe the role of sexual reproduction and fertilisation in creating variation within a population.
During the meiosis phase crossing over and random assortment of chromosomes create unique combinations of genetic material this resulting in the zygote having aa unique set of combinations thoat both different of both parents. This creating variation which is crutial in evaluation of a species as genetic variation is created which is also important for the adaptions of populations and changing environments.
