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DNA Replication

structure of DNA implies replication -->
- antiparallel
-base pair bonding
-H+ bonds


1/2 old and 1/2 new
Daughter strand --> 1 parent DNA and 1 new DNA


Original is original. Copies are copies. NOT way DNA is replicated.

DNA Replication

Bases are added sequentially
Daughter DNA is identical to parental DNA

Enzymes Specific Jobs

topoisomerase/helicase --> unwinding, straightening DNA out
primase --> primes the site, starts the process
polymerase --> lays down nucleotides
ligase --> glues the ends together

Leading and Lagging Strand

DNA is stable as double strand
Once DNA is opened, become fragile so binding proteins bind to strand making it stable
Leading --> 1 continuous strand
Lagging --> pieces of DNA glued together

Functions of Cell Division

-growth and development
-tissue renewal

Cell Cycle -Interphase

G1 Phase - growth -->adding pieces
S Phase - DNA synthesis --> takes about 7 hours
G2 Phase - growth --> adding pieces


-small portion of cycle
-occurs after growth and synthesis
-division of nucleus


-complete structure


-single copy of duplicated DNA (attached)


-all of the nuclear material


-where sister chromatids are attached
-where spindle fibers attach during mitosis


-organize spindle fibers


-division of nucleus
- 5 phases --> prophase, prometaphase, metaphase, anaphase, and telophase


- 1st phase --> visibility phase
- condensation of chromosomes
-centrosomes appear and migrate
-spindle fibers appear


-breakdown of nuclear membrane
-spindle fibers attach to centromeres


- chromosomes pair up
- chromosomes align randomly on plate/center
-spindle fibers visible


- centromeres divide
-sister chromatids move to opposite poles


-nuclear membrane reforms
-chromosomes uncondense
-spindle fibers disappear
- cell division begins


-cells divide out of control
-"checkpoints" during each phases of the cell cycle
- cells ignore checkpoints


-Benign --> slow growing and harmless (warts and moles)
-Malignant --> invades adjacent tissue (metastasizes)

Differences of Cancer Cells and Normal Cells

- cancer cells divide uncontrollably
- immortal --> normal cells die after about 50 cycles, cancer cells can survive 100's-1000's cycles; telomerase --> there for protection, munched on like RNA tail so after about 50 cycles it's gone and good DNA is munched on
-various growth factors
-lack contact inhibition -->lack control and push other cells out of the way so that's why you get lump

Causes of Cancer

-environment (UV light, chemicals, etc.)
-most causes can be eliminated through education

Risk Factors of Cancer

-tobacco use
-lack of exercise
-UV exposure
-poor diet
-virus exposure

Treatments for Cancer

-killing abnormal cells with either chemotherapy or radiation therapy
-removing abnormal cells through surgery


-programmed cell death
-human approx. 50 cycles
-aging or defective cells
-also in development --> create spaces for fingers and toes


- enzyme that unwinds the DNA in preparation of replication

Binding Proteins

-Stabilize each strand because DNA becomes very fragile when opened up


- enzyme that add short RNA primer to template strand

DNA Polymerase

- enzyme that binds nucleotides to form new strands
-proofreads as it goes along


- joins Okazaki fragments and seals the nicks in sugar-phosphate backbone

Okazaki Fragments

- short pieces of DNA from the lagging strand

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