Cell division - june 4

reasons for cell reproduction

• asexual reproduction

• growth and development

• replacement (regeneration) of lost cells

• repair

prokaryotic cell division includes

• binary fission

• chromosome duplication

• cell growth

• fission

the splitting of one parent cell into two identical daughter cells

binary fission

splitting of the parent cell

fission

preparation period for eukaryotic cell division

interphase

interphase of eukaryotic cells includes:

• G1 period

• S period

• G2 period

period of cell growth in interphase

G1 period

• period of DNA synthesis in interphase

• chromosome duplication

S period

each chromosome is copied and a centromere bond attaches the copy to the original

S period of interphase

a period of mass cell structure in interphase

G2 period

each duplicated chromosome consists of two sister chromatids bonded together by a

centromere

what extends from the centromere

kinetochore

phases of eukaryotic cell division

1. interphase

2. mitotic phase

   1. mitosis

      1. prophase

      2. metaphase

      3. anaphase

      4. telophase

3. cytokinesis

what phase is this of eukaryotic cell division?

• Nuclear division  

• 1. prophase  

• 2. metaphase  

• 3. anaphase 

• 4. telophase  

• Cytokinesis- 

mitotic

when chromosomes become thick and visible, the nucleolus disappears, mitotic spindles form, nuclear envelope breaks

prophase

an arrangement of microtubules called spindle fibers

• attached to centrioles in animal cells

mitotic spindle

lining up of duplicated chromosomes along the middle to the cell

• (equator plate)

metaphase

• Separation and pulling apart of sister chromatids  

• Spindle fibers shorten and centromere bonds break  

• Sister chromatids (daughter chromosomes) pulled to opposite ends of a cell  

anaphase

• Formation of two new nuclei in which daughter chromones can be place  

• Nucleoli appear  

• Mitotic spindle of spindle fibers breaks down  

• Chromosomes thin out and de-condense to chromatin  

telophase

division of a parent cell into two identical daughter cells

• cleavage furrowing

• tumor development

cytokinesis

cytokinesis for animal cells

• a contracting ring of microfilaments pulls inwardly on the cell membrane

cleavage furrowing

due to uncontrolled cell division and inaccurate chromosome duplication

tumor development

the sum of all chemical reactions occurring within a cell or organism

• can be categorized by what occurs during the reaction

metabolism

reactions that involve the breaking down of molecules

• hydrolysis, cellular respiration

catabolism (catabolic reaction)

reactions that involve the building of molecules

• dehydration synthesis, photosynthesis

anabolsim (anabolic reaction)

reactions that yield (produce) more energy than what is required

• more out than in

  • hydrolysis, cellular respiration

exergonic reactions

reactions that require more energy than what is yielded (produced)

• more in than out

  • dehydration synthesis, photosynthesis

endergonic reactions

catabolic reactions are typically

exergonic

anabolic reactions are typically

endergonic

regulatory proteins that regulate all metabolic (chemical) reactions

• acts as catalyst

• lower activation energy

• 3-D molecules

• designed to act upon certain substrates

enzymes

what does it mean that enzymes lower activation energy

they lower the amount of energy necessary to start a reaction

a substrate shape must be what to the shape of the active site

complementary

the region of an enzyme where substrates bind

active site

an inorganic mineral or metal that attaches to an enzyme and allows it to accept substrate

cofactor

organic vitamins that attach to an enzyme and allows it to accept substrate

• these molecules must bind to the enzyme first in order for the substrate to connect with the active site

coenzymes

stops an enzyme from working temporarily

• competitive

• noncompetitive

enzyme inhibition

a molecule binds to the active site of an enzyme and prevents the normal substrate from binding

competitive inhibition

a molecule binds to an enzymes at a spot other than the active site and indirectly prevents the normal substrate from binding

noncompetitive inhibition

what do these factors effect?

• time

• substrate

• enzyme concentration

• temperature

• pH

enzyme activity

an increase in time will yield what in enzyme activity

increase in activity

An increase in enzyme concentration will yield an what in enzyme activity  

an increase

An what in substrate concentration will yield an increase in enzyme activity  

INCREASE

changes the shape of the active site and prevent substrates from binding

• no product produced

• from excessively temperature

denature enzyme

the most favorable pH for maximum enzyme activity

• for most = 7.0 (neutral)

optimum pH

unfavorable pH results in what of enzymes

denaturing

an unfavorable pH is any pH

outside the optimum range