Bio 12-14

fertilized egg

• Heals wounds
• Replaces damaged cells
• Growth
• Reproduction (only on that incudes meiosis)

all DNA in a cell

• One molecule of DNA is wrapped around proteins to form a chromosome
• contains hundreds of genes

section of DNA that has the instructions for making one protein

• DNA needs to be doubled
• Each newly made daughter cel must receive the exact amount of genetic material as the parent cell

Location of a gene

• Results in two identical DNA molecules
• Exactly the same b/c of base pairing rule

where sister chromatids are attached

• Interphase (cell growth and copying of chromosomes in preparation for cell division)
• Mitosis
• Cytokinesis (division of cytoplasm)

INTERPHASE OR CYTOKINESIS

Interphase

• G₁ = Gap 1
• G₂ = Gap 2
• S = DNA Synthesis

• The cyclin-dependent kinase (Cdk) transfers phosphates and only works when cyclin is present.
• Control whether cells get through checkpoints or not
• Cell makes cyclin when ready to move on
• protein + ATP --> protein-P +ADP

• Division of nucleus
• Followed by cytokinesis (cytoplasm division)
• Purpose: separate sister chromatids so each new cell has complete set of chromosomes - exact genetic match to original cell

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

long stringy form of DNA strands - condesnse to chromosomes, which condense further

• Chromosomes condense
• Nuclear membrane dissolves
• Mitotic spindle forms

Microtubules attach to kinetochores (proteins) at one side of the centromere

• Chromosomes align along lateral plane
• Microtubules shorten and eventually centromere can't hold any more

Separate sister chromatids (separate exact DNA copies)

• Chromosomes migrate to poles
• Prepares for cytokinesis
• Nuclear membrane reforms

Cytoplasm divides in clevage furrow (outside-in) in animals

Unregulated cell division

• Mass of cells with no function
• can be benign or malignant

doesn't afect surrounding tissues

invades surrounding tissues; cancerous

cells break away from a malignant tumor and start a new cancer at another location

• Cancer cells:
• Divide when they should not
• Invade surrounding tissues
• Move to other locations in the body

Change in the info that a gene carries or a change in the sequence of nucleotides of a DNA molecule

• substances that damage DNA and chromosomes
• Ex: cigarette soke, UV light

• Before cancer genes
• says go or not go (conditions must be right)

• cancer gene
• says go, go, go, no matter what

stops tumors from forming if there is an oncogene

One must have an oncogene AND a mutated tuor suppressor in order to get cancer

• Angiogenesis (vessel formation)
• Immortality (don'r dies as long as the have the oxygen and nutrients needed)
• Lack of contact inhibition (when they come in contact with each other, they don't stop dividint like skin cells, rather pile up)
• Lack of anchorage dependence (allows for metasticization)

scientific study of heredity and variation

transmission of traits from one generation to the next

units of heredity; made up of segments of DNA

• reproductive cells
• have one set of chromosomes (23 total)
• produced by meiosis

• nonreproductive cells
• have 2 sets of chromosomes (46 total)
• produced by mitosis

22 pairs of chromosomes that do not determine the sex

sum of all homologous chromosomes in a cell

2 chromosomes in each pair

• 2n
• 2 sets of chromosomes
• Humans diploid number is 46 (2n=46)

• n
• containsa single set of chromosomes
• Human haploid number is 23 (n=23)

• reduces the numver of chromosome sets from diploid to haploid
• Preceded by replication of chromosomes
• Two sets of cell division (Meiosis I an meiosis II)
• Results in 4 daughter cells

Meiosis I and Meiosis II

• Homologous chromosomes separate
• Reductional division

• Sister chromatids separate
• Equational division

Homologous chromosomes pair by adhering along their lengths

Chromosomes begin to condense

• Tetrds line up at metaphase plate
• Microtubules attach

Homologous chromosomes separate

• Each half of cell has haploid set of chromosomes
• Each chromosome still consists of 2 sister chromatids

spindle apparatus forms

Sister chromatids line up at metaphase plate

Sister chromatids separate and move as individual chromosomes toward opposite poles

• Nuclei form
• Chromosomes begin decondensing

• Cytoplasm separates
• Four daughter cells formed, each with haploid set of unreplicated chromosomes

• Independent assortment of chromosomes (meiosis)
• Crossing over (meiosis)
• Random fertilization (where sperm meets egg)

• every time we go through meiosis might give a diff arrangement
• 1st place to get genetic diversity

• takes place in Prophase I
• Inside chromosomes flip flop ends
• 2nd place to get genetic diversity

• Any sperm can fuse with any ovum
• The fusion of 2 gametes (each with 8.4 milion possible chroosome combinations from independent assortment) produces a zygote with any of about 70 trillion diploid combinations