Download Chapter 2: How Chromosomes Work

How Chromosomes Work
The DNA Molecule
1. DNA— deoxyribonucleic acid
2. Watson and Crick—discovered the structure of DNA; received the Nobel Prize for
Physiology and Medicine in 1962 for their discovery; structure of DNA is a
double helix (twisted ladder)
3. gene—smallest unit of heredity
4. DNA molecule—structure of a gene
5. Relationship between DNA molecule and genes-- genes are composed of segments
of a DNA molecule
6. DNA function—controls the production of proteins
7. DNA segment (draw and label)—See me or a friend for this information.
8. nitrogen base pairs—molecules that contain the element nitrogen
 adenine
 thymine
Adenine pairs with Thymine
 cytosine
 guanine
Cytosine pairs with Guanine
9. genetic code—order of nitrogen bases provides the code for particular proteins
Example:
ATCCGGAAT
TAGGCCTTA
2-4: How Chromosomes Produce Proteins
10. new cell formation—cells reproduce by dividing; the new cells contain the exact same
genetic information as the original cell, and the new cells are called daughter cells
11. DNA replication—process of making exact copies of DNA; DNA replication is the
first step of the cell cycle
12. DNA replication steps—
a) DNA strand “unzips”
b) Free nitrogen bases pair up with bases on “unzipped” strand of DNA
c) New bases attach and two strands of DNA are formed that are identical
**See drawing on notebook paper.
13. role of chromosomes—chromosomes control the production of proteins because they
are made of a long strand of DNA
14. protein body functions—proteins determine all traits and they help to build and repair
cells
15. protein synthesis—process of producing proteins
**See drawing on notebook paper.
16. RNA (name and role)—RNA stands for ribonucleic acid; RNA “reads” the genetic
code on a strand of DNA and helps to guide protein synthesis
17. RNA vs. DNA--
RNA
DNA
Single strand (one side)
Double strand (two sides)
Sugar: ribose
Sugar: deoxyribose
Adenine pairs with Uracil
Adenine pairs with Thymine
18. messenger RNA vs. transfer RNA—
messenger RNA
Abbreviation = mRNA
Copies code from DNA and carries it
out of nucleus
transfer RNA
Abbreviation = tRNA
Transfers code from mRNA to ribosome
so that protein synthesis can occur