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READING GUIDE UNIT 3
CHAPTER 1
What are the main elements found in organic molecules?
Carbon, Hydrogen, Oxygen, Phosphorus, Sulfur
What are the 4 main types of organic macromolecules?
Carbohydrates, lipids, proteins, nucleic acids
Carbohydrates contain which elements?
Carbon, Hydrogen, Oxygen
In what ratio do you find H and O?
2:1
Sugar-phosphates often contain what polyatomic group?
Phosphate
Give an example of a monosaccharide and a disaccharide.
Glucose, sucrose
Plants and animals have different polysaccharides. Name the plant polysaccharides.
Starch, cellulose
Which plant polysaccharide is not digestible by humans? What is our common name for
it?
Cellulose, fiber
Where do animals store their polysaccharides?
Liver and muscle in the form of glycogen
Lipids are made of what two main components?
Glycerol and fatty acids
List the purposes of lipids in the body.
Long term energy storage, cell membranes, cholesterol
What type of lipid makes up cell membranes?
Phospholipids
What is the difference between saturated and unsaturated fats?
Saturated = no double bonds
unsaturated = double bonds
Which one is liquid at room temperature?
Unsaturated
Which one is found in animals?
Saturated
Give me the good and the bad about steroids and cholesterol.
Our bodies need them to function but too much can harm the body
What roles do proteins play?
Structural components, messengers, body defense, ENZYMES
What are the building blocks of proteins?
Amino acids
What are the 4 parts of an amino acid?
H, acid group, amino group, R group
How many different R groups are there?
20
What kind reaction joins amino acids together?
Dehydration reaction
What is the bond between amino acids called?
Peptide bond
A long chain of amino acids are called?
Polypeptide chain
Explain what a primary, secondary and tertiary protein structures are?
Primary- the sequence of amino acids
Secondary- simple folding of the amino acid chain
Tertiary – complex folding that makes a globular structure
What do we mean when we say that structure determines function?
Sequence of a.a. determines the shape which determines very specific
functions within the bodies of organisms
What role do nucleic acids play in organisms?
Determine a.a. sequence, source of genetic information
Nucleic acids are made up of nucleotides. What are the three parts of a nucleotide?
Sugar, phosphate, base
How do purines and pyrimidines differ from each other?
Purines are double rings and pyrimidines are single rings
How do RNA and DNA differ from each other?
RNA – single strand, ribose sugar, uracil, can leave the nucleus
DNA – double strand, deoxyribose sugar, thymine, cannot leave the nucleus
Draw a strand of DNA with 4 bases.
What shape does DNA form?
Double helix
What is a triplet codon?
Three nucleotides that code for an a.a.
Chapter 8
1. Summarize the four phases of the eukaryotic cell cycle.
a. Growth (G1,) duplication of DNA (S phase,) growth (G2,) nuclear and
cell division (Mitosis)
2. What determines if a cell stays in interphase or divides?
a. Signals from the surroundings (the need to divide)
3. Briefly describe the structure of a DNA molecule.
a. Side chains of alternating deoxyribose and phosphate with
nitrogenous base pairing connecting the side chains
4. Describe the role of each of the following enzymes
a. Helicase – unwind DNA
b. DNA polymerase – adds DNA nucleotides
c. RNA polymerase – adds RNA primer
d. Ligase – connects DNA fragments
5. Why can DNA have more than one replication origin moving in opposite
directions when DNA polymerase only works in one direction?
a. Because eukaryotes have way more DNA and it would take too long
b. Eukaryotes have a leading and a lagging strand
6. Why are Okazaki fragments produced?
a. Because DNA polymerase only works in one direction producing a
lagging strand with fragments
7. Describe the role that histones play in condensing a strand of DNA.
a. DNA wraps around histones to make the basic packing unit
8. Describe the different mechanism for error and damage repair.
a. DNA polymerase proof reads its work
b. Excision and repair – excise the incorrect DNA sequence and
polymerse adds correct nucleotides, backbone is sealed
Chapter 9
1. How does DNA serve as a master program for organisms?
a. Genetic information is stored on DNA, this info determines protein
structure/function, proteins carry out important cell functions
2. What roles does RNA serve in the expression of genetic information?
a. Carries temporary copy of gene to ribosome
b. Carries correct a.a. to ribosome to produce polypeptide chain
c. Make up the ribosome that produces the polypeptide chain
3. What does the genetic code describe?
a. A sequence of bases in DNA or RNA that translates into a.a. in
protein.
4. How many “words” does the code require? What do the “words” represent?
a. 3, a nucleotide
5. Where is the codon found?
a. mRNA
6. Where is the anticodon found?
a. tRNA
7. What is an enzyme?
a. Biological catalyst – speeds up the rate of a reaction
8. What is so important about a proteins structure?
a. Structure dictates function
9. What is the purpose of the RNA polymerase?
a. Put down an RNA primer for DNA polymerase to use
10. Is transcription more complex in prokaryotes or eukaryotes? Explain.
a. Eukaryotes are more complex with more DNA polymerases
11. What is the job of each of the three types of RNA?
a. rRNA makes up ribosomes, tRNA brings a.a. to the ribosome, mRNA
carries the genetic code out of the nucleus to the ribosome.
12. LIST the steps in transcription.
a. DNA Polymerase attaches to promoter region of DNA
b. Unwinding and adding of nucleotides
c. Termination and release of RNA
13. What are the three stages of transcription?
a. Initiation, elongation, termination
14. What are the three steps in RNA processing and what are their purposes?
a. mG cap help protect from enzymes that break it down
b. poly A tail same as above
c. remove introns – non coding regions
15. What is tRNA charging?
a. Adding an a.a.
16. What is the job of each ribosomal binding site?
a. E – exit of used tRNA
b. P – pairing a growing a.a. chain
c. A – accept new tRNA with a.a.
17. What dictates the amino acid sequence?
a. DNA  mRNA
18. What are the three stages of translation?
a. Initiation, elongation, termination
19. What happens at each of the stages?
a. Initiation – ribosome comes together on start codon, first tRNA comes
in
b. Elongation – more tRNA's come to the ribosome and a.a. are
connected with peptide bonds to form a chain
c. Termination – a.a. chain is released when stop codon is reached
20. Are all protein chains immediately functional? Why of why not?
a. No, they need to be modified and/or transported if they have a signal
sequence
21. How do cells send proteins to the correct location?
a. Membrane vesicles made from the golgi body.
22. List types of translation errors and their consequences?
a. Frame shift
b. Splicing errors