Biology Ch. 12.1-2 Ch. 10 Study Guide

Showed genetic information passes from one cell to another
Discovered DNA stores and transfers genetic information
Hershey & chase
Confirmed genetic material is DNA
Showed DNA as double helix (twisted ladder)
Watson & crick
Built first model of DNA
A=t & g=c
Chargaff’s rule
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Building block if DNA
Deoxyribose sugar, phosphate group, nitrogen base
3 parts of a nucleotide
Purines and pyrimides
2 categories of nitrogen bases
Adenine & guanine
2 purines
Thymine & cytosine
2 pyrimidines
Double helix or twisted ladder
Shape of DNA
Deoxyribose sugar & phosphate
Makes up sides of DNA ladder
Hydrogen bonds
Holds nitrogen bases together
Deoxyribose sugar
Where nitrogen bases branch from sides of ladder
Adenine to thymine, cytosine to guanine
Base pairing rule (what bonds to what)
DNA replication
The process by which DNA is copied
Step 1 of DNA replication
DNA double helix unwinds
Step 2 of DNA replication
Enzymes break hydrogen bonds separating DNA in 2
Step 3 of DNA replication
Each 1/2 serves as a template for a new complementary strand
Step 4 of DNA replication
Free nucleotides match to the halves by an enzyme called DNA polymerase
Step of DNA replication
2 identical DNA’s are formed
Problems when a cell is too big-
Difficult to transport nutrients and waste
(Answer- problems)
Initiates cell division
Longest part of cell cycle
G1, S, & G2
3 steps if interphase
G1 phase
Cell grows, DNA chromatin
S phase
When DNA replication occurs
Sister chromatids
2 identical lengths of DNA
Holds chromatids together
G2 phase
When organelle replicate
Nuclear division
4 phases of mitosis
Prophase, metaphase, anaphase, telophase
Chromosomes lie up at the middle of cell
Centromeres split & chromosomes travel to opposite poles
Difference in plant and animal cells
•Animal- centrioles
• plants- no centrioles
( spindle fibers in both)
When spindle forms, chromosomes visible as sister chromatids, nuclear membrane disappears
When chromosomes spread out
Disappears, nucleus reappears
Division of cytoplasm
Cytokinesis in animal
Cytoplasm pinches together
Cytokinesis in plants
Cell plate forms then becomes the cell wall
Final result f cell cycle
Two identical daughter cells were formed
Protein that regulates timing of the cell
Uncontrolled cell growth resulting in tumors
Damage caused by cancer
Damage surrounding tissue, break loose and spread to other parts of body, disrupt normal cell activities
Defective gene
Halt the cell cycle
Stem cells
Unspecialized cells that can differentiate