5.2 Flashcards
what is a model?
A model is a 3D representation of a particular structure. Models are often effective communicating the idea and behaviour of a particular structure. However, they are often oversimplified, lacking structural details, and are not to scale.
what happens if an incorrect replication occurs and how can it turn out.
well it will result likely in a mutation. this mutation will either be favourable or disadvantageous. Favourable being it causing variation whilst a con creating unfavourable traits, impairing dna replication and protein synthesis
what are chromosomes composed of?
they compose of histones, DNA, and genes
homologous chromosomes have….
have identical genes, but each chromosome of the homologous pair may code for a different ‘variant’ of the gene, termed allele. one variant is usually dominant whilst the other is recessive
what r three factors that identify mitosis
-occurs in all body tissues by somatic cells
-produces two genetically identical diploid daughter cells
-occurs for the purpose of growth, repair and maintanence
what are the stages of mitosis
ipmat
interphase
prophase
metaphase
anaphase
telophase - cytokenesis
what must be done before interphase for mitosis to occur
the somatic cell must be present which is a diploid cell and homologous. This is the parent cell thatll be utilised for the process
what occurs in interphase of mitosis
DNA undergoes replication.
There should be two identical copies of chromosomes (4n). In human cells, its going from 46 strands of DNA chromosomes to 92. Longest phase
What occurs in prophase of mitosis (3)
DNA condenses into chromosomes of an x shape and joins its sister chromatid at the centromere
- Nuclear membrane disappears
- The spindle fibres are preparing for metaphase to attach to the chromosomes
what occurs in metaphase in mitosis
the chromosomes align in the middle along the equator
- Centrioles move to the poles
- Spindle fibres which are created from the centrioles extend from it and attach at the centromeres of the chromosome
what occurs in anaphase of mitosis
Spindle fibres pull the chromatids towards the opposite side of poles.
what occurs in telophase of mitosis
the nuclear membrane reforms.This is where cytokinesis begins as cell cleavage is visible.
what is cytokenesis in mitosis
cytokinesis is the physical splitting of the daughter cell into two done by microfilaments. Microtubules contract and pinch the cells apart.
what is meiosis and whats the key difference from mitosis
a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes
what is the role of meiosis?
- During sexual reproduction, two parents are involved in passing genetic material on to offspring.
- To prevent the chromosome number from doubling in each generation, meiosis occurs and produces gametes with half the full number of chromosomes.
what is the difference between diploid and haploid
diploid
containing two sets of chromosomes
* Chromosomes are in PAIRS, homologous chromosomes
- 2 copies of each chromosome (one maternal, one paternal)
haploid
* Containing one set of chromosomes
* Cells have half the full number of chromosomes
* ONE of each pair
* Chromosomes are single