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Why do cells divide
For reproductions, for growth and development, for repair and replacement
When dividing cells what has to be copied
DNA, organelles, cell membrane, lots of other molecules, enzyme
A dividing cell..
Duplicates it’s 1
Chromosome of human female
X
Chromosome of human male
Y
DNA structure
Double helix, 2 sides like a latter
A pairs w
T
C pairs with
G
Copying DNA steps
Replication, unzips its double stranded molecule
To build DNA strand it has to…
Use original parent strand as template, add new matching bases
When a cell is ready to divide…
Copy DNA first, coil up doubled chromosomes, now it can move DNA around cell without having it tangle and break
What happens in the interphase stage
Copies DNA
What happens in the prophase stage
DNA is wound up into chromosomes to keep it organized
What happens in the metaphase stage?
Chromosomes line up, attach to protein cables that will help them move
What happens in the anaphase stage?
Chromosomes split, separate pairs, start moving to opposite ends
What happens in the telophase stage?
Cells start to divide, nucleous forms again
What shoe ones in cytokinesis stage?
Cells separate, now can do every day jobs
New daughter cells get ______ copies of original cells
2 exact
What did Watson and crick do?
Developed double helix model of DNA
What does the DNA backbone refer to.
Refers to the 3’ and 5’ ends of DNA
Purines in DNA
Adenine, Guanine
Pyrimidines In DNA
thymine, cytosine
base pairing allows each strand to serve as _____ for a new strand
Template
What’s the ratio of parent template and new DNA in a new strand of DNA
½ and ½
What unwinds DNA
helicase enzyme
What is the unwinded part of DNA helix stabilized by?
Single stranded binding protein
What’s the complementary bases in a daughter DNA stand
DNA polymerase III
Where does energy for bonding usually come from?
Proteins
The nucleotides arrive as:
Nucleosides
P-P-P=
Energy for bonding
DNA bases arrive with _______________ source for bonding
their own energy
Lagging strand:
Okazaki fragments, joined by ligase, “spot welder” enzyme
Leading strand
Continuous synthesis
DNA polymerase I
Removes sections of RNA primer and replaces with DNA nucleotides
DNA polymerase I still can only building onto _____________________
3’ end of an existing strand
DNA polymerase III
1000 bases/section, main DNA builder
DNA polymerase I
20 bases/section, editing,repair, and primer removal
DNA polymerase reduces error rate from:
1 in 10000 to 1 in 100 million bases
What is E. Coli
Bacteria found in the lower intestine of warm-blooded organisms.
It takes _______ 1 hour to copy 5 million base pairs in its single chromosomes
E. Coli
Human cell copies it’s 6 million bases and divide into daughter cells in cells in only few hours which is?
Remarkably accurate
What is the relationship between chromatin and chromosome
Chromatin is unwinded chromosomes
What is the role of centrioles
To help sister chromatids separate
During which 3 phases are individual chromosomes no longer visible
Cytokinesis, interphase, telophase
When is mitosis a good thing?
When you have to add or replace cells
When is mitosis a bad thing
When cells reproduce and are not needed
What does cancer damage?
Organs
When dna get damaged and cells stop listening to correct instructions what happens?
Mutations
Causes of mutation:
UV radiation, cigarette smoke, chemical exposure, radiation exposure, heat, pollution, age, genetics
Benign tumor
Abnormal cells remain at original site as a lump, most don’t cause serious problems and can be removed by surgery
Malignant tumor
Cells leave original site, damage functions of organs throughout body
What are the two treatments that kill rapidly dividing cells
Chemotherapy, radiation
Chemotherapy
Poisonous drug that kill rapidly dividing cells
Radiation
High energy beam that kills rapidly dividing cells
Mitosis components
Produce cells with same information, exact copies, Same number of chromosomes
Single cells eukaryotes
Yeast, paramecium, amoeba
Simple multicellular eukaryotes
Hydra
Do we make egg + sperm by mitosis?
No
Human female karyotype
23 pairs XX
Human male karyotype
23 pairs XY
How do we make sperm and eggs?
Must reduce 46 chromosomes to 23
When you half the number of chromosomes what’s it called?
Haploid
Homologous chromosomes
Both chromosomes of a pair carry matching genes
Characteristics of 1 division of meisosis
4 chromosomes, diploid, 2N
Meiosis 2 overview
2nd division of meiosis, looks like mitosis, 2 chromosomes, haploid, 2N
Meiosis makes what
Gamates
Mitosis makes what
Copies of cells
How does mitosis making copies of cells help?
Growth, repair, development
The value of meiosis 1
Consistency over time, meiosis keeps chromosomes some from generation to generation
Value of meiosis 2
Change over time, meiosis imtroduces genetic variation, gametes of offspring do not have same genes as gamete’s from parents, new combo of traits
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