DNA

Why is it important?
- Contains hereditary material
- Directs cell function
WHAT THREE THINGS
MAKE UP DNA?

1. phosphate
2. deoxyribose sugar
3. nitrogenous bases
WHERE ARE THEY FOUND?
-nucleus
DESCRIBE THE SHAPE OF
DNA

sugar backbone
-nitrogenous bases bonded
with a hydrogen bond
“double helix”
-
WHAT ARE THE 4
NITROGENOUS BASES?

- Adenine (A)
-Guanine (G)
-Cytosine (C)
- Thymine (T)
WHICH ONES PAIR
TOGETHER?

Adenine-Thymine A-T
Guanine-Cytosine G-C
*PURINES-double ring of carbon &
nitrogen
Adenine & Guanine
*PYRIMIDINES-single ring of carbon &
nitrogen
Cytosine & Thymine
COMPLEMENTARY
BASES

GATTACA
CTAATGT
DNA REPLICATION

WHEN DOES IT OCCUR?
“S” phase of interphase
WHY DOES IT OCCUR?
because the cell divides
THREE STEPS OF
REPLICATION

1. helicase separates double
helix “unzips” it
2. DNA polymerases add
complementary nucleotides
3. DNA polymerases finish
replicating DNA and fall off

WHAT IS A
MUTATION?

An incorrect nitrogenous base
is added to a DNA molecule.
WHERE IS THE MUTATION?
CATGATC
GTACAAG
FOUR TYPES OF
MUTATIONS

1.
2.
3.
4.
Deletion
Insertion
Inversion
Duplication
PROTEINS AND RNA

WHAT IS A GENE?
A segment of DNA that is
located on a chromosome and
that codes for a hereditary
character.
HOW DO GENES
DETERMINE OUR
TRAITS?

The gene directs the making of a trait
WHAT IS THE NAME OF THE
PROCESS THAT CREATES Mrna
FROM A DNA SEQUENCE?
Transcription
WHAT IS THE PROCESS THAT
CREATES A PROTEIN FROM
mRNA?

Translation
WHY ARE PROTEINS IMPORTANT
TO EVERYDAY LIFE?
They do important work in cells,
such as protecting the body against
infections and carrying oxygen in RBC
WHAT ARE AMINO
ACIDS?

An organic molecule that
makes up proteins. The amino
acid will determine the shape
of the protein and the shape is
critical to the proteins function
RNA VS DNA

Sugar ribose
sugar deoxyribose
Contains AUGC
Contains ATGC
Single stranded
double stranded
Shorter
long

BOTH nucleic acids made up a
nucleotides
THREE TYPES OF RNA

Messenger RNA (mRNA)
Ribosomal RNA (rRNA)
Transfer RNA
(tRNA)
RNA JOBS?

mRNA- carries the instructions
from a gene from DNA to
ribosomes
rRNA-make up ribosomes
tRNA-transfers amino acids to
the ribosome to make a protein.
RNA TRANSCRIPTION

TAKES PLACE IN THE:
Nucleus in eukaryotic cells and
DNA region of cytoplasm or
prokaryotic cells
THREE STEPS IN
TRANSCRIPTION?

1. RNA polymerase binds to
promoter(initiates transcription)
2. RNA polymerase adds free
RNA nucleotides that are
complementary to the nucleotides
on one of the DNA strands.

3. RNA polymerase reaches a
termination signal. Upon
reaches this “stop” signal, RNA
polymerase releases both the
DNA and the newly formed
RNA.

RNA POLYMERASE

An enzyme that catalyzes the
formation of RNA on a DNA
template
TERMINATOR SIGNALa specific sequence of nucleotides
that marks the end of a gene
COMPLEMENTARY BASE
PAIRING

ATCCGATTA
 RNA- UAGGCUAAU
 DNA-
RNA TRANSLATION

Making of proteins
WHAT IS INVOLVED IN THIS?
 translation or decoding of genetic
instructions to form a polypeptide
WHY IS IT IMPORTANT?
proteins are critical for living things
5 STEPS OF
TRANSLATION

1. (initiation) tRNA and mRNA
join together. Enzymes attach a
specific amino acid to one end of
each tRNA according to the
genetic code.
2. (elongation)The polypeptide
chain is put together

3. (elongation) The polypeptide
continues to grow
4. (termination) ribosome reaches
the stop codon. The newly made
polypeptide falls off.
5. (disassembly) The ribosome
complex falls apart.

CODON

-The three nucleotide sequence
in mRNA that encodes an
amino acid or signifies a start
or start signal
AUG-start
UAA, UAG- stop
HOW DO YOU KNOW WHAT
AMINO ACIDS ARE ADDED
TO A PROTEIN
CHAIN?

By using the genetic code