Bio Lab quiz 4 part 1

• Duplication of self (does not require 2 gametes)
• Replicating DNA
• Mitosis is this type of cell division

• Advantages: Takes less energy
• Disadvantage: No variabity=No adaptation (bad for natural selection)

• Gametes (haploid,n) come together during fertilization to produce offspring
• MEIOSIS

• Advantages: increased variation
• Disadvantages: requires more energy

40% DNA and 60% protein

Only condensed during cell division. At other times it is uncoiled (found at the expressed portions of DNA)

Always condensed (portion of the DNA in not expressed)

One of two identical strands of a chromosome

Sister chromatids: two identical copies of a chromatid connected by a centromere.

When two strands seperate they are called DAUGHTER CHROMOSOMES.

A single piece coiled DNA, mad of chromatin

Homologous chromosomes: Two different copies of the same chromosome (can be single or double stranded)

• Mitosis: results in the seperatin of replicated chromosomes into two identical daughter nuclei
• -somatic cell: body cells, two sets of chromosomes (diploid,2n)

• Meiosis: results in daughter cells with 1/2 chromosomes of the parent cell
• -gamete: sex cells, one set of chromosomes (haploid,1n)

the period between mitotic and meiotic division in which there is cell growth and DNA replication.

Division of one cell into two cells

• (longest phase)
• G1: gap1 synthesis of mRNA for use in protein synthesis (takes 6-12)
• S: synthesis, DNA is synthezied (replicated), going from one chromatid to sister chromatid (6hours)
• G2: gap 2, synthesis of molecules and structures needed for mitosis (5hours)

• Control mechanisms that ensure cell division is proceeding acurately.
• G1/S: check for enough proteins, general health of cell, and DNA damage.
• G2/M: looks at DNA damage that occured during replication.
• -Apoptosis (cell suicide)
• -Go back to interphase and correct process

• Condensing of the chromosomes (easier to move)
• Nuclear membrane begins to breakdown
• Nucleoli disappear
• Beging to form spindles (Actin fibers)
• Maturation of kinetochores (proteinaceous material on the sides of the centromere)

• Kinetochores attach the chromosomes to the spindles
• chromosomes align along the mitotic plate
• There is also a spindle checkpoint

• Seperatin of chromosomes
• Sister chromatids begin to move towards the poles via spindles (forming identical cells)

• Cytokinesis occurs (cell plate formation in plants and cleavage furrow in animals
• Spindles dissasemble
• Kinetochores disappear
• Nuclear membrane reforms
• Nucleoli reappear
• Chromosomes become uncondensed

• Interphase: prepare
• Prophase: condense
• Metaphase: line up
• Anaphase: split
• Telophase/Cytokinesis: two new dipliods

• •Pre-meiotic Interphase:
• –prepare cell for division
• –replication of chromosomes

• •Prophase I:
• chromosomes condense
• –Formation of spindles and centrioles
• –Homologous chromosomes pair in synapse forming tetrads

–Crossing over and recombination (chiasmata)

• •Metaphase I:
• –Tetrads line up
• –Chromosome position is random (independent assortment of chromosomes)

• •Anaphase I:
• –Homologous chromosomes separate

• •Telophase I:
• –One chromosome of each pair arrives at pole
• –Cytokinesis occurs

• •Interkinesis (Interphase II):
• –Cell prepares for division
• –NO DNA replication

• •ProphaseII:
• –Chromosomes reappear
• –Spindles form
• –Nuclear membrane breaks down

• •MetaphaseII:
• –Chromosomes line up

• •AnaphaseII:
• –Sister Chromatids separate

• •TelophaseII:
• –Chromatids arrive at poles
• –Cytokenesis occurs

• Males:
• •Maintain many cells (spermatogonia) that
• are diploid and can constantly undergo mitosis

• •Two daughter cells (primary
• spermatocytes) go through meiosis to produce four haploid cells (spermatids)

•Spermatids mature into sperm

•Process takes 9 weeks