CHAPTER 8 – HOW GENES WORK (DNA)

UNDERSTANDING DNA

There were ___ major groups of scientists that researched DNA (whether they were trying to or not!)

_____________________________ discovered that genetic material, or DNA, could be transferred between living & dead bacteria.

He was trying to identify two strains of Pneumococcus bacteria, when he observed  _______________________, a process in which a bacterium takes up foreign DNA.

One strain of Pneumococcus formed ___________________ colonies, and one strain formed __________________ colonies. To determine which bacteria were virulent, he injected BOTH strain into mice. This is what happened… (Figure 8-1) GRIFFITH’S EXPERIMENT:

Griffith found that:

• Non-harmful bacteria became _________________
• ________________________________ had been transferred between _____________ & _______________ bacteria

____________________ identifies the agent of transformation.

Was the substance that made nonvirulent bacteria -> virulent bacteria _________________ or _____________?

Experiment 1

• He extracted __________ from bacteria in _____________ colonies -> bacteria in _______________ colonies
• Some of the bacteria from this mixture formed _______________ colonies

Experiment 2

• When he added __________________________________________________ to bacteria, TRANSFORMATION still occurred
• When he added ___________________________________________________ to bacteria, TRANSFORMATION CEASED!!!!

His research proved that __________________________________________________ in these bacteria

Each organism has a _____________________ combination of characteristics encoded in _________________________________________

___________________________ & _________________________ confirmed that DNA is the genetic material.

They performed an experiment using _________________________________ sulfur (______) & phosphorus (______), & viruses that infect bacteria.

This is what happened: (Figure 8-2)

What did they conclude?

• Viruses had injected ____________ into cells
• Viruses caused infected _______________ to make new ______________
• __________ is the hereditary material

How Scientists Determined the Structure of DNA

 Scientists KNEW that DNA: 

• Composed of long chains of ________________ called __________________
• Each ___________________ consists of:

* ____________________________ (Deoxyribose)

* ____________________________

* ____________________________ (TWO groups)

                        __________________ - larger, two-ringed bases (ADENINE, GUANINE)

                                                __________________ - smaller, single ringed bases (CYTOSINE, THYMINE)

• Structure of a nucleotide:

_____________________________ developed ______________________________.

A = T, C = G

(The amount of Adenine = the amount of Thymine in a DNA molecule, and the amount of Cytosine = the amount of Guanine)

_____________________________ used X-Ray diffraction images to suggest that DNA resembles a tightly coiled spring, a shape called a ________________.

___________________________ & __________________________ (1950’s) built a model proving the structure of DNA is a _______________________  _____________________, composed of two strands of nucleotides held together by hydrogen bonds. They won the ____________________________ in 1962.

REPLICATION - HOW DNA IS  COPIED

_____________________________ - The process of copying DNA. This must occur ____________________  ____________________________________________

The 2 strands of the double helix are _____________________ to one another, which means that the ____________________ of _____________ on one strand determines the sequence of bases on the other strand.

When the strands are separated, a _____________________________________ is made from the original.

The process of ____________________ involves several __________________-

• One enzyme _________________________ & _________________ the 2 strands
• Another enzyme, _________________________, adds nucleotides to the exposed DNA strands.

During ________________________, a ________________________ strand of DNA is made for each original strand of DNA. For EXAMPLE, if a portion of the original, or “______________” strand is CCTAGCT, the new strand will be GGATCGA.

What will be the complementary strand of DNA if the original strand reads TAGCCATTG  ?

                                                                                                                         _____________

A ____________________ is a change in DNA. This can occur if a base is accidentally inserted, left out, or substituted for another base during replication. This can result in ____________________  __________________, which can turn out to be lethal. For example, ________________________________ is a  single gene disorder in which ___________________ is substituted for another. An entirely different ___________________ is produced, resulting in sickled (misshapen) Red Blood Cells, anemia, heart disease & kidney disease.

A ____________________ is an environmental agent such as ultraviolet light & chemicals that can cause defects in DNA structure, or ___________________.

HOW PROTEINS ARE MADE

________________________________ - The use of the genetic information in DNA to make proteins.

2 Stages of Gene Expression: 

• ___________________________ - RNA (Ribonucleic Acid) copy of a gene is made (DNA -> RNA)
• ___________________________ - 3 different kinds of RNA work together to assemble amino acids into a protein molecule.  (RNA -> Protein)

DNA   -> (transcription) ->   RNA    -> (translation) ->   PROTEIN

HOW DNA MAKES RNA (TRANSCRIPTION)-

• _________ is copied within the ________________
• _________ copies are sent out of the ________________ to direct the assembly of ______________.
•  These working copies of _____________ are _____________ strand of ____________

THREE TYPES OF RNA:

• ________________________________ - Located in the NUCLEUS. Can LEAVE the nucleus to make proteins for the DNA
• ________________________________ - Located in the CYTOPLASM . Carries amino acids to the ________________________
• ________________________________ - Located in the CYTOPLASM. Makes up the ______________________

_____________________________ - Genetic information encoded in _________ is transferred to an ________ molecule

• ______________________ binds to a region of ______ called a _________________
• ______________________ unwinds the double helix & ________________ the 2 strands
• RNA Polymerase moves along one strand of DNA like a train on a track. As it moves, ________________________  ___________________ pairing takes place between the _______ strand & the _____________________
• _______________________ joins these ____________________ one after another, forming a ____________________ strand of nucleotides.
• This continues until a specific “___________” sequence in the DNA is reached
• ______________________ detaches from DNA, _______ strand drifts free and passes out of nucleus into _____________________ 

The Genetic Code

Every ______ nucleotides in ______ specifies a particular _________________________

Each of these ________________________   ____________________ is called a ________________.

The ____________________ of amino acids in a __________________ determines:

• Which __________________  __________________ will be added to a growing ________________ chain
• The _____________________ & ____________________ of a ___________________

(REFER TO GENETIC CODE TABLE FROM BOOK)

__________________________________ - Correspondence sequence between nucletide triplets in _________ and amino acids in ___________________

Any of the ______ bases (A, U, C, G) found in ___________ can occur at any of the _____ positions of a ______________.

Thus, ______ different possible ________________________ are possible in the genetic code. (4X4X4 = 64)

Since there are ______ possible _____________, but only ______ different ___________________________, more than ____ codon may specify a single _______________________

START Codon __________ initiates the start of protein production.

STOP Codons _________, __________, & ___________ specify the _______ of an __________________ sequence, or ____________________.

The code contained in a particular gene results in a ___________________  ____________________.

HOW RNA MAKES PROTEINS - TRANSLATION

_____________________________ - The process by which a genetic message is deciphered.

• Occurs in the ____________________, on ______________________.
• _____________________ are complex organelles that contain a special kind of RNA called ___________________________________. They are made of 2 subunits. _________________ use ___________ to direct assembly of __________________.

What happens?

• __________ binds to a specific site on the small _________________________
• Large __________________________ attaches to form a complete ribosome with a strand of _____________ running through it.
• Small _________________________ binds to ____________________________
• ___________ acts as an __________________ because it carries _____________________ to the correct codon on the ___________________
• On the ___________ molecule is a 3-nucleotide sequence called an _____________________, which is ___________________ to the __________  codon. This ___________________ ensures that each amino acid is delivered to its proper “____________________” on the ___________ as the ____________________ is assembled.
• ________ passes along the ribosome, and one ________ after another is selected to match the sequence of __________ codons.
• _____________________ are added until a ___________ codon is encountered.
• _____________________ complex (large & small subunits) falls apart
• Newly assembled __________________ is released into ____________