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Cell Biology Student Outline – DNA Structure and Function I
DNA Structure and Function I
1.
Introduction to DNA
A.
Forms
i.
Chromatin
ii.
Chromosome
B.
Chemical Makeup
i.
Nucleotide
a.
Deoxyribose
b.
Phosphate Group
c.
Nitrogen Containing Base
•
•
•
•
C.
Anenine
Guanine
Thymine
Cytosine
Molecular Construction
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Cell Biology Student Outline – DNA Structure and Function I
i.
Basic Construct
ii.
Double Stranded
a.
Complimentary Base Pairing
•
Thymine – Adenine
•
b.
Guanine – Cytosine
Hydrogen Bonds
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Cell Biology Student Outline – DNA Structure and Function I
c.
2.
Double Helix
Replication of DNA
A.
DNA Helicase
B.
DNA Polymerase
i.
Continuous
ii.
Discontinuous
C.
DNA Ligase
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Cell Biology Student Outline – DNA Structure and Function I
3.
Transcription and Translation
A.
Overview of Processes
1.
2.
3.
4.
5.
6.
The genetic material for eukaryotic organisms (includes humans) is
DNA. The information is divided up into functions segments called
genes. Each gene will code for a particular structural or functional
molecule necessary for cellular growth and maintenance. In this
case we will assume that the gene codes for a particular enzymatic
protein.
Transcription of the information from DNA into RNA (called mRNA
or messenger RNA). This transcription process is necessary as
ribosomes can only work with RNA.
The messenger RNA leaves the nucleoplasm via a nuclear pore
and enters the cytoplasm.
First the small and then the large ribosomal subunits attach the to
the mRNA in order to translate the genetic material into a protein.
As they translate the mRNA they add the appropriate amino acids,
according to instruction, to a growing polypeptide chain. Note that
multiple ribosomes can do the translation process simultaneously
(called a polysome).
After a ribosome has finished translating the mRNA, the two
ribosomal subunits and the newly formed protein disengage the
mRNA.
The ribosomes can then repeat the process and translate the
mRNA once again.
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Cell Biology Student Outline – DNA Structure and Function I
7.
B.
C.
The newly formed protein enters the cytoplasm to do it’s particular
cellular function.
Ribosomes (rRNA)
i.
Structure
ii.
Function
Transcription
i.
RNA Polymerase
ii.
Nucleotides
a.
b.
iii.
DNA Nucleotides
•
Thymine – Adenine
•
Guanine – Cytosine
RNA Nucleotides
•
Uracil – Adenine
•
Guanine – Cytosine
Process of Transcription
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Cell Biology Student Outline – DNA Structure and Function I
iv.
Codes and Codons
v.
mRNA
vi.
mRNA Procession
a.
Exons
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Cell Biology Student Outline – DNA Structure and Function I
b.
D.
Introns
Translation
i.
Transfer RNA (tRNA)
a.
Anticodon
b.
Amino Acid Binding Site
DNA
Code
mRNA
Codon
tRNA
Anticodon
Amino
Acid
TTT
TGG
CCG
CAT
CTC
GAG
AGA
ACT
AAA
ACC
GGC
GUA
GAG
CUC
UCU
UGA
UUU
UGG
CCG
CAU
CUC
GAG
AGA
ACU
Lysine
Threonine
Glycine
Valine
Glutamate
Leucine
Serine
“Stop”
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Cell Biology Student Outline – DNA Structure and Function I
ii.
4.
Steps of Translation
a.
Initiation
b.
Elongation
c.
Termination
Regulation of Gene expression
A.
Transcription Control
i.
Chromatin Activation
ii.
Transcription Factors
B.
Posttranscriptional Control
C.
Translational Control
D.
Posttranslational Control
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