cell replication Flashcards
what is cell replication
a form of cell division in which a parent cell divides
what are reasons for cell replication
growth/development, maintenance/repair, method of asexual reproduction in prokaryotes
what are the phases of the cell cycle
interphase (G1,S,G2)
mitosis
cytokinesis
what happens in interphase
DNA replication occurs to produce two copies of each chromosomes
define chromatids
two identical chromosomes held together at the centromere
define chromatid
one half of a duplicated chromosome
define centromere
where chromatids connect
what happens in the metaphase
Chromosomes align at equatorial plane of cell, Spindle fibres attach to centromeres of chromosomes, No nucleus
what happens in anaphase
-Spindle fibres contract, splitting the centromeres and separating the sister chromatids
-The separated chromosomes are pulled to opposite poles
what happens in telophase
Nuclear membrane reforms around the two sets of chromosomes, Spindle fibres disappear
what happens in prophase
Chromosomes become clear and nucleus starts to break down, centrioles move to opposite sides of the nucleus and form spindle fibres
what happens in cytokinesis
There is 2 new cells
Cytoplasm divides resulting in two identical cells known as daughter cells
what is a limitation of modelling mitosis
the model is static and doesn’t show the fluid nature of the mitosis process
what is meiosis
cell division resulting in four daughter cells (gametes), each with half the number of chromosomes (haploid) of the parent cell and are not identical
what is the difference of meiosis to mitosis in the PROCESS of cell division
-during metaphase I, chromatids meet in the middle in pairs
-there is two rounds of mitosis
-results is four daughter cells that are not identical
what are the similarities of mitosis and meiosis
-both are cell replication
-both undergo interphase, prophase, metaphase, anaphase, telophase and cytokinesis
whats the difference of mitosis and meiosis
Meiosis: produces four haploid daughter cells (gametes), process happens in the GONADS (testes for males and ovaries for women), not identical to parent cell, number of chromosomes will be half to parent cells
Mitosis: produces two diploid daughter cells identical to the parent, occurs in SOMATIC cells (every cell but sex cells), does not change genetic information, number of chromosomes will be same to parent cell
recall the process of mitosis
see notes
recall the process of meiosis
see notes
model nucleotides
includes phosphate, pentose sugar and nitrogenous base
see notes for model
what does A, T, C and G, stand for? what are the complementary pairs
A= adenine pairs with T= thymine (apples in the trees)
C= cytosine pairs with G= guanine (cars in the garage)
what is the structure of DNA?
DNA is a double stranded helix (spiral), like a ladder. Nitrogenous bases (steps of the ladder) a sugar-phosphate backbone (sides of the ladder)
what do nucleotides form?
Nucleotides chemically bond to form nucleic acids e.g. deoxyribonucleic acid (DNA)
Describe the process of DNA replication using the Watson and Crick model
DNA unzips → by helicase enzyme
DNA polymerase brings nucleotides to complementary base pairs from 5’ to 3’
One strand has the bases joining one by one and the other strand has okazaki fragments attached to the bases
Okazaki fragments is when more than one base attaches at a time
The two identical sets of DNA coil back into a double helix
DNA ligase enzyme seals new strands together
This process is semi-conservative
Why use a model for processes?
as you can’t see these processes with the naked eye therefore allowing people to have access to seeing the process without an extreme microscope that is usually inaccessible, makes it simple and easier to understand
What is the bond of nucleotides that holds DNA together called?
phosphodiester bonds
what is the pairing and bonding process in DNA replication
Free nucleotides bond together (sugar bonds to phosphate) through a condensation polymerization reaction
Hydrogen bonding holds bases together inside a DNA helix (2 between A and T, 3 between G and C)
What is the importance of DNA replication
-DNA replication ensures that the daughter DNA strands carry the same genes, therefore coding for all the essential proteins necessary for life
-For cell division to happen DNA needs to be replicated
-If DNA is not replicated before cell division (meiosis and mitosis), daughter cells would have inadequate amount of DNA and genetic information
what does cell division achieve? (its importance)
for organisms to reproduce and grow in order for their species to survive
importance of mitosis
-Produce identical nuclei, which is identical genetic content to their parents cell
-ensures growth and repair of an organisms therefore allowing them to survive long enough to reproduce (species continuity)
-allows genes to be passed
-asexual reproduction
importance of meiosis
-if there is no egg or sperm (gametes) an organism cannot be produced and therefore the species cannot continue
-Meiosis creates varied combinations of genes that can be passed onto the next generation because gametes have a haploid set of chromosomes
-This variation allows species better opportunities to deal with selective pressures, ensuring the continuity of species through evolution
How important is it for genetic material to be replicated exactly?
-Allows cell division within meiosis and mitosis -Mitosis is a form a asexual reproduction, as it produces new organisms DNA replication allows the continuity of a species
-Produces the right amino acids to create the proteins needed in our body
