1
WHAT IS GENETICS AND WHY DO WE STUDY IT?
Genetics is the study of heredity
and the variation of inherited
characteristics.
Reasons to study genetics:
 its central importance to all
life on Earth,
 medical benefits such as cures
for diseases,
 better food crops.
2
There are 2 types
of nucleic acids
-DNA
-RNA
DNA
DNA is often called
the blueprint of life.
 In simple terms, DNA
contains the
instructions for
making proteins
within the cell. (Proteins

made by ribosomes!)
4
RNA
present in all living
cells
 Its role is to act as a
messenger carrying
instructions from
DNA for controlling
the synthesis of
proteins

WHAT ARE NUCLEIC ACIDS MADE OF?

Nucleic acids (a macromolecule) are made up
of long chains of monomers called nucleotides
Each nucleotide is made up of 3 parts

a phosphate group (PO4)

a sugar (deoxyribose or ribose)

a nitrogenous base (GCAT or U)

NUCLEOTIDES
A phosphate group bonded to one of the 2 sugars
that is bonded to one of the nitrogenous bases
bond
bond
P
phosphate
Sugar
DRAW THE NUCLEOTIDE
base
THE DIFFERENT SUGARS
Ribose (RNA) is a 5 carbon ring sugar (C5H10O5 )
Deoxyribose (DNA) is also a 5 carbon sugar, but
lacks one oxygen atom C5H10O4
Quick check
What are the 2 types of nucleic acids?
What are nucleic acids made of?
What are the 3 parts of a nucleotide??
What are the 2 types of sugars?
WHERE IS DNA FOUND?
 Our
genes are on our
chromosomes.
•
floats in the
cytoplasm of all
prokaryotic cells
10
THE SHAPE OF THE MOLECULE
 DNA
is a very long
polymer.
 The
basic shape is like a
twisted ladder or zipper.
 This
is called a double
helix.
11
ONE STRAND OF DNA
nucleotide

One strand of DNA is
a polymer (multitude)
of nucleotides.
12
3
Remeber Each DNA nucleotide is made up of…
a phosphate
group
PO4
a sugar
deoxyribose
A nitrogenous base
G or C or A or T
base
The nitrogenous bases of DNA and RNA are
Guanine
G
Cytosine
C
Adenine
A
Thymine
(DNA only)
T
Uracil
(RNA only)
U
5
10
The bases always pair up in the same way
Guanine always bonds with Cytosine and C with G
Cytosine
Guanine
Adenine forms a bond with Thymine and T with A
Adenine
Thymine
Remember: Gangster CAT has DNA
Soulja Boy likes RNA…why??
Quick check
What are the 2 sugars found
in nucleic acids?
How many nucleotide bases
are there?
Name one possible base.
Which base is only found in
DNA? RNA?
CHARGRAFF’S RULE:
Adenine and Thymine always join together
Cytosine and Guanine always join
together
17
Chargaff’s Rule
What conclusions can you make?
Organism
%A
%T
%G
%C
Mycobacterium
tuberculosis
Yeast
Wheat
Sea Urchin
Marine Crab
Turtle
Rat
Human
15.1
14.6
34.9
35.4
31.3
27.3
32.8
47.3
29.7
28.6
30.9
32.9
27.1
32.1
47.3
27.9
28.4
29.4
18.7
22.7
17.7
2.7
22.0
21.4
19.9
17.1
22.8
17.3
2.7
21.3
21.5
19.8
OVER VIEW OF
RNA
Made of nucleotide
subunits chained together
Single strand of
nucleotides
5 carbon sugar, ribose
Nucleotide bases G, C, A,
U (uracil)
DNA VS. RNA
DNA
Made of nucleotide
subunits chained together
Double strand of
nucleotides
5 carbon sugar,
deoxyribose
Nucleotide bases G, C, A,
T (thymine)
• Go to next blank ION page.
• Turn it sideways
• Set up a double bubble map
for DNA and RNA
DNA
RNA
DOUBLE BUBBLE
DNA
RNA
DNA REPLICATION AND PROTEIN SYNTHESIS
DNA REVIEW

Deoxyribonucleic Acid –
composed of building
blocks called nucleotides



Phosphate
Sugar (deoxyribose)
Nitrogen bases
Adenine – Thymine
 Guanine – Cytosine



Right hand twist
Double stranded
http://accessexcellence.org/RC/VL/GG/index.html#Anchor-From-14210
QUICK REVIEW

Chromosomes: Tightly coiled strands of DNA

Each chromosome contains genes
 Characteristics/traits
passed down through
generations

The genes on a chromosome produce proteins
 This
is how you see a trait!
WHAT’S IN A GENE?



sequences of nucleotide bases; passed
down from parent to offspring
These Genes code for polypeptides
(proteins)
All cells require proteins to function, thus
they have many genes!
MORE ABOUT PROTEINS!

Proteins are made of amino acids linked
together by peptide bonds
20 different amino acids
exist

Amino acid chains are
called polypeptides

FROM DNA TO PROTEINS


DNA is found in the
nucleus of a cell

RNA and proteins are
found outside of the
nucleus

How does this happen?
1.
2.
3.
The major steps:
Replication of DNA
Transcribe to RNA
Translate to Protein
PATHWAY TO MAKING A PROTEIN
DNA
mRNA
tRNA (ribosomes)
Protein
28
DNA  RNA  PROTEIN
Nuclear
membrane
DNA
Transcription
Eukaryotic
Cell
Pre-mRNA
RNA Processing
mRNA
Ribosome
Translation
Protein
29
16
STEP 1: REPLICATION
•
process of producing
two identical
replicas from one
original DNA
molecule
•
•
•
First unzip
Next copy
Finally 2 identical
strands
17
THE STRANDS SEPARATE
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
Each strand builds up its partner by adding
the appropriate nucleotides
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
18
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
REVIEW

What is the copying of DNA into 2 strands
called?

How much of the strand created is new
material?
STEPS 2 AND 3

Protein synthesis
 process
by which the genetic code puts together
proteins in the ribosomes

2 main steps
 Transcription
 Translation
STEP 2: TRANSCRIPTION
Double stranded DNA
is unzipped
 One side is the
template (pattern) and
the other builds the
mRNA

 mRNA=
messenger
RNA
 Carries
genetic info to
ribosmes

This process happens in
the nucleus
IN-BETWEEN STEPS 2 AND 3

Once the mRNA has been created it leaves the
nucleus and heads to a ribosome
STEP 3: TRANSLATION

Now the mRNA is in the cytoplasm traveling to
the ribosome

Once there, it binds to a ribosome
STEP 3: TRANSLATION
 The
bases of the
mRNA strand are
read in sets of 3
A
set of three is
known as a
codon/triplet
 Each codon will
specify 1 of the 20
different amino
acids
STEP 3: TRANSLATION

Once bound to the
ribosome tRNA reads
the codons on mRNA
and transports the


tRNA=transfer RNA
The anticodons are
connected to a specific
amino acid
STEP 3: TRANSLATION

The ribosome connects the amino acids
together into a chain called a polypeptide chain

Polypeptides chains are just amino acids linked
together. This is what makes a protein!

POP QUIZ!!!!!!

Take out 1 sheet of paper
Write your name
 Number 1-6

QUESTION 1
Which of the following are components of
nucleotides?
(a) deoxyribose
(b) amino acids
(c) phosphate
(d) enzymes
(e) organic bases
QUESTION 2
Which of the following represent a correct
pairing of bases?
(a) adenine with thymine
(b) adenine with guanine
(c) thymine with adenine
(d) guanine with cytosine
(e) thymine with thymine
QUESTION 3
DNA molecules are formed from
(a) organic bases
(b) amino acids
(c) deoxyribose
(d) nucleotides
QUESTION 4
Which of the following are nucleotide bases?
(a) Valine
(b) Guanine
(c) Thymine
(d) Serine
QUESTION 5
Replication of DNA occurs
(a) During cell division
(b) before cell division
(c) at any time
QUESTION 6
A codon/triplet codes for
(a) a protein
(b) an amino acid
(c) an enzyme
(d) an organic base