Biology
DNA & the Language of Life
Genes are Made of DNA

Fredrick ________________________________________________ (1928) studied
pneumonia strains (one was harmless while the other was
_________________________________________, or disease-causing)
o Made non-harmful strains harmful
(_______________________________________________)
o Discovered the ‘transforming
___________________________________________’ was genetic material

Oswald ___________________________________________ (1944) confirmed that
the genetic material was ___________________________________________

Alfred __________________________________ & Martha
________________________________________ performed the
‘__________________________________________ experiments’ using a virus
(specifically a bacteriophage, or virus that infects a bacteria), bacteria, and
radioactively labeled probes.
o They concluded that _______________________________ was the genetic
material.
Structure of DNA
Structure determines function.

DNA is made up of ______________________________________________.

A nucleotide is made up of a 3-carbon sugar called a
__________________________________, a __________________________________
group (PO ) and a ______________________________________________________.
3

There are 4 nitrogenous bases in DNA: __________________________________ (A),
Guanine (G), __________________________________(T), and Cytosine (C).

A & G are __________________________________________ and are larger than
________ & ________which are pyrimidines.

Edwin __________________________________________ (1950’s) discovered that in
different species there is always an equal number of A’s and T’s and an equal
number of C’s and G’s.
o These findings are Chargaff’s ______________________________________.
o Adenine matches with ____________________________________ and
Cytosine matches with ____________________________________.

A purine matches with a pyrimidine. (a large base matches with a small base,
making DNA have a ________________________________________ width
throughout).

Maurice _________________________________ and Rosalind
_______________________________________ (1952) used x-rays to photo DNA &
discovered that DNA has a spiral shape.
o Unfortunately, this x-ray was taken by another scientist, James
_______________________________________ who realized what the x-ray
revealed.

James Watson and Francis ________________________________ (1953) published
their results (and received the Nobel Prize).
o They received credit for discovering the
________________________________ of DNA.

DNA is _______________________________________ stranded & a
_________________________________________________ (or twisted ladder).

This double helix is formed by 2 strands of
___________________________________________________________________.

Each strand is composed of nucleotides: the ________________________________
and ______________________________________ bind to each other to form the
“backbone” of the ladder while the nitrogenous _______________________________
form the “rungs”.

Each rung is formed with 1 purine bonded with 1 pyrimidine (A-T or C-G).
DNA Replication:

This is DNA copying itself. This occurs during
___________________________________________ (synthesis) of Interphase.
What happens?

DNA _____________________________(unzips): enzymes open the base pairs
and hold the double helix apart.

Each DNA strand acts as a __________________________________ for DNA
replication for a new complimentary strand

_______________________________________________ join the original strand 1
at a time

DNA ______________________________________________is the enzyme
responsible for the base-pair matching

This is called ____________________________________________________
replication because the new DNA that results has 1 old strand of DNA and 1 new
strand of DNA. Watson & Crick hypothesized this as well.
Gene Protein

George ________________________________________ & Edward
_________________________________________ hypothesized ‘one gene-one
enzyme’ (based on their work w/ bread
____________________________________ Neurospora crassa).

From this hypothesis, it has been discovered that many genes code for
polypeptides (but they are specific): ___________________________________one polypeptide (part of a protein)
From Genotype to Phenotype

Protein Synthesis is the __________________________________________ of a
protein.
o This is taking the organism’s
___________________________________________ (genetic makeup) and
translating into the ____________________________________________ (the
physical traits).
o DNA is made up of nucleotides (bases).
o The bases make up a ________________________________________.
o Genes ______________________________________ for the sequence of
amino acids (a.a.).
o _____________________________________ code for proteins.
o Therefore, DNA is a template for making proteins.
o An _________________________________________________ gene is a gene
that codes for a protein that is synthesized.
There are 2 types of nucleic acids: DNA and RNA.

___________________________________= ribonucleic acid.
RNA differs from DNA
RNA

Is ______________________________________ stranded

Contains ________________________________________ (U) instead of thyamine (T)

Has a _______________________________________ instead of a deoxyribose
There are 3 types of RNA:

mRNA is _______________________________________ RNA

__________________________________________ is transfer RNA

__________________________________________is ribosomal RNA
Protein Synthesis occurs in 2 stages:
1. Transcription:

_________________________________ is copied

_________________________________ is synthesized or transcribed

This occurs within the _______________________________________________
What happens during transcription?

RNA _______________________________________________ (enzyme that is
responsible for RNA synthesis) separates the DNA double helix & matches RNA
bases with 1 DNA template only.

This is specifically making ____________________________________________.

Instead of T, U is inserted. (U binds with A, C binds with G)

Only _____________________________________ strand is made.

In prokaryotes, mRNA goes directly to the
_________________________________________ (there is no nucleus).

In eukaryotes, mRNA is _______________________________________________.

Splicing is when noncoding regions called
_____________________________________________ (junk DNA) are removed
and coding regions called ______________________________________ are
sealed together.
o Both introns and exons are copied during transcription.
o After splicing, mRNA leaves the
_______________________________________ and finds a ribosome.
2. Translation:

This is when nucleic acids are changed, or
_________________________________________, into the language of proteins
(amino acids).

This involves _____________________________,
___________________________, and ___________________________.

It occurs on a __________________________________ (either free or attached to
the ER, depending on where the protein is going).
What happens during translation?

_________________________________ attaches to a ribosome.

A tRNA molecule “transfers” or brings over an __________________________
forming an amino acid chain; With each additional a.a. the chain grows longer.

tRNA brings the correct a.a. over based on the complementary codons &
___________________________________ (base sequences)

a ________________________ is a base sequence on the mRNA strand. This
codes for a specific a.a.

An anticodon is 3 bases found on tRNA that ___________________________ the
codon.
Example:

Codon= GCU on mRNA (codes for alanine, an a.a.)

Anticodon= CGA on tRNA
The Triplet Code

tRNA wil ultimately be translated into amino acids.

______________________________ amino acids & 64
____________________________

3 ________________________ codons (UAA, UGA, UAG) & 1 start codon
(________________) which also codes for methinionine (met)
Mutations: Changes in Chromosomes

Proteins have various functions: they may act within the cell OR serve a purpose
outside of the cell. They may be activates or repressors (turning genes on or off).

A ________________________________________is a random change in the DNA
(sequence of nucleotides).
o This can be ____________________________________ mutations (which
involve entire chromosomes) or _______________________________
mutations (which involve individual genes).

A mutagen is an ___________________________________________ factor that
causes a DNA mutation, like radiation and chemicals.

A carcinogen is a __________________________________ causing agent (this is also
a mutagen).
o These can be tars in cigarette smoke, UV radiation, and other chemicals.