Bio 8.txt

• Reproduction of individual cells
• Parent cell splits into 2 daughter cells

The structures that contain most of a cell's DNA

• The creation of genetically identical offspring by a single parent
• Done without sperm/eggs

• Requires fertilization of an egg by a sperm
• 2 parents

• Type of cell division
• "dividing in half"

• Fibers composed of half DNA and half protein molecules
• Too thin to be seen under a light microscope

• 2 copies of each chromosome attached together
• Identical copies of DNA

• Tightest spot sister chromatids are attached
• Like the waist

• Sequence of events from
• When a cell forms until it divides itself into 2

• 90% of cell division
• 3 stages- g1 (first gap), s (synthesis) and g2 (second gap)
• Duplicates chromosomes; cell doubles in size in preparation for division
• Centrioles prepared

• Part of the cell cycle when the cell actually divides
• About 10% of the time
• 2 identical daughter cells produced

• Part 1 of mitotic phase
• Nucleus and contents, like DNA, duplicate

• Cytoplasm divides in 2
• Usually overlaps with mitosis

• The chromatin becomes chromosomes visible with a light microscope
• Sister chromatids join together at centromere
• Mitotic spindle starts to form- microtubules grow

• Nuclear envelope fragments and disappears
• Microtubules reach defined chromosomes- attach to kinetochore
• Chromosomes move to center of nucleus

• Mitotic spindle fully formed
• Chromosomes on metaphase plate in between two polls of spindle
• Microtubules attach specific chromosomes

• Centromeres come apart
• Sister chromatids separated- moved to opposite ends of the cell
• Cell elongates

• Cell elongation continues
• Nuclear envelopes begin to form
• Chromosomes uncoil into chromatin
• Cytokinesis stars
• Cleavage furrow forms

Football shaped structure of microtubules that guide the separation of the sets of sister chromatids

• Microtubules for mitotic spindle emerge from 2 centrosomes
• Cytoplasmic material that contains pairs of centrioles
• Microtubules organizing centers

• A shallow indentation in the cell surface
• Start of cytokinesis
• Eventually pinches parent cell in half

• Fused vesicles that form a membranous disk
• Grows outward and eventually fuses with the plasma membrane to create to daughter cells

• A protein secreted by body cells that stimulates other cells to divide
• ie. Injury causes new skin to grow

• Cells only divide until a surface is covered
• Crowded cells don't continue dividing
• Not present in cancer cells

Cells won't divide when not in contact with a aloud surface

• Set of molecules that trigger and coordinate key events in the cell cycle
• Cells must get the signal at certain stages to begin or continue dividing. It doesn't happen automatically
• Without approval to move to S stage, cell enter G0 and never divides-muscle cells

An abnormal cell thy escapes detection

• Cells that remain at the original site of creation
• Usually easily removed in surgery
• Only a real problem if they grow in a spot that disrupts organs like the brain

• Can spread into neighboring tissues and other parts of the body
• Displaces tissue and interrupts organs as it grows

A person with cancer has a malignant tumor

• When cancer cells spread beyond their original location
• Spread when cancer cells get in blood stream

Cancers that start in the skin or internal body coverings like the lining of the intestine

Cancers that start in tissues that support the body like bone or muscle

Cancers of blood-forming tissues like bone marrow

Cancers in blood-forming tissues like lymph nodes

• A typical human body cell
• Contains 46 chromosomes

• Two chromosomes of a matching pair
• Similar in size, shape, banding pattern and loci location

A particular spot on a chromosome that holds the gene for a specific trait

• X and Y chromosomes
• In males, the only non-homologous chromosome pair
• Females have 2 Xs and males have an X and a Y

• All chromosome pairs except sex chromosomes
• 22 pairs in humans

• Development of a fertilized egg into a new adult organism
• The sequence of stages leading from one generation to the next

• All body cells contain pairs of homologous chromosome
• Abbreviated 2n

• Egg and sperm cells
• Single set of chromosomes
• Haploid cell
• Abbreviated n

• A cell with a single chromosome set
• Humans have 23 chromosomes per haploid cell

When a sperm cell fuses with an egg cell

• Product of fertilization
• 2 sets of homologous chromosomes- one set from each parent
• Diploid

• Cell division that produces haploid gametes in diploid organisms
• Similar to mitosis except 2 stages- meiosis I and meiosis II (closer to mitosis)

Set of four chromatids

An exchange of corresponding segments between non-sister chromatids of homologous chromosomes

• Sites of crossing over
• Appear as an X shaped
• region
• A place where two nonsister chromatids are attached

Production of gene combinations different from those carried by the parent chromosomes

An ordered display of a person's chromosomes condensed and doubled like in mitosis

• An extra chromosome 21
• A total of 47 instead of 46 chromosomes
• Causes down syndrome

• Affects 1/700 children
• Most common birth defect in the US
• Frequently causes a round face, a skin fold in the inner corner of the eye, a flatter nose, small teeth, and short stature
• Also causes heart defects, and mental retardation

• Occasional mishap where chromosomes fail to separate
• Occurs during either meiosis I or II

• Caused when a chromosome fragment is lost
• Cause serious physical and mental problems

When a fragment joins with a sister chromatid or a homologous chromsome

• Less likely to cause serious problems
• Fragment reattaches to chromosome but flipped
• Chromosome still there so less dangerous

• When a fragment attaches to a non homologous chromosome
• Exchange segments
• May or may not be harmful
• Often cancerous