Relavent Cell Replication and DNA Replication Flashcards
What happens in mitosis interphase?
The cell grows and duplicates its DNA+organelles (centrioles)
What happens in mitosis prophase?
- Chromatin condenses into chromosomes
- Mitotic spindles begin to develop
- Nuclear envelop breaks down
What happens in mitosis metaphase?
- Spindles align at the poles
- Chromosomes align along the equator
What happens in mitosis anaphase?
Kinetochore microtubules pull chromosmes towards poles
What happens in mitosis telophase?
- Chromosomes decondense
- Nuclear envelope reforms
- Spindles dissapear
How is meiosis M1 different from mitosis metaphase?
Chromosomes align in homologous pairs along the equator (rather than one line). They have already been in pairs since prophase 1.
What are the differences between mitosis and meiosis?
- Mitosis is used in growth and repair of cells
- Mitosis also produces identical daughter cells only whereas meiosis produces gametes
How do genetic stability and genetic variation contribute to the continuity of the species?
The inheritance of characteristics from ancestors to currently living organisms relies on the passing of consistently accurate information AND the occasional introduction of new genetic information. Accurate DNA replication brings about genetic stability, whereas mutations bring genetic variation.
What does mitosis produce
2 diploid cells (2n)
What does meiosis produce
4 haploid cells (n)
What is an allele?
An allele is one or two or more versions of DNA sequence (a single base or a segment of bases) at a given genomic location
What are the 4 steps in DNA Replication?
Topoisomerase, SSBP, L&L, RNA primase synth RNA primer, DNA ligase.
- Topoisomerase relaxes the double helix while helicase breaks hydrogen bonds between nucleic acids, unzipping the DNA strand. Single Strand Binding Protein (SSBP) stabilises the unzipped parent strands
DNA POLYMERASE CAN ONLY BUILD THE STRAND FROM 5’ TO 3’ (opp of original) - The leading strand (3’-5’) is continuously synthesised by DNA polymerase. This involves only one RNA primer
- The lagging strand (5’-3’) is synthesised discontinuously. DNA primase synthesises a short RNA primer (per each section), which is extended by DNA polymerase to form Okazaki fragments
- After the RNA primer is replaced by DNA, DNA ligase joins the Okazaki fragments to the growing strand
What are the names and purposes of the four main enzymes involved in DNA replication?
- Helicase: unzips the helix and breaks hydrogen bonds
- Primase: synthesises short RNA sequences that are complementary to a single-stranded piece of DNA at the replication fork
- DNA polymerase: to replicate new DNA strands
- Ligase: to join Okazaki fragments and errors in the leading strand
Which end is the leading and lagging strand synthesised from?
Leading (3’ to 5’)
Lagging (5’ to 3’)
What occurs in prophase 1?
Chromosomes decondense and the nuclear envelope breaks down. Homologous chromosomes line up. Crossing over occurs
