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DNA

The

molecule of

heredity 1

• __________ = passing on

of characteristics from parents to offspring

•How? . . . _____

HEREDITY

DNA! 2

DNA

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I. DNA, Chromosomes, Chromatin and Genes

• ______ = blueprint of life (has the instructions for making

an organism)

• ___________ = uncoiled DNA

• ______________ = coiled DNA

DNA

Chromatin

Chromosome

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• You have ___ chromosomes or ___ pairs in the ________ of

each body cell.

• _____ from Mom and

_____ from Dad

nucleus

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• _______ = a segment of DNA that codes for a protein, which in turn codes for a trait (skin tone, eye color, etc); a gene is a stretch of DNA.

–There is a gene for every protein your body has to make.

Gene

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II. DNA

• Deoxyribonucleic Acid

• Located in the

___________________

• Codes for your _______

• _____________

discovered DNA in 1928

nucleus of the cell

genes

Frank Griffith

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A. Shape and Structure

• DNA nucleotide components:

1. _____________

(simple sugar)

2. ___________

_______

3. _______________

(A,T,C,G)

Deoxyribose

Phosphate group

Nitrogen bases

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• Shaped similar to a twisted ladder . . . therefore . . .

____________ !

• The uprights of this

ladder are composed of ____________ and

___________________

double helix

phosphates

deoxyribose sugar

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B. Base Pairing • 1953:

___________________________________

discovered the DNA double helix.

James Watson and Francis Crick

What you may not

know is that without

___________________ they would have

never made their

discovery.

Rosalind Franklin

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DNA

• The rungs are

composed of 2

bases (a purine

and pyrimidine)

joined at the

center by weak

__________

bonds.

hydrogen

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DNA

• _________ = adenine (A) and guanine (G)

• _____________ = thymine (T) and cytosine (C)

Purines

Pyrimidines

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Direction of the two DNA strands:

• ___ = orientation of the sugar has carbon on the left

• ___ = orientation of the sugar has carbon on the right

5’

3’

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Direction of the two DNA strands: • The _____ strand is oriented 5’-3’ and

the ________ strand is opposite 3’-5’ top

bottom

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B. Base Pairing • 1962:

___________________________________

discovered that A always bonds with T and C bonds with G

James Watson and Francis Crick

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DNA

• _________ and _________ are complementary. They both

require ___ hydrogen bonds.

• __________ and _________ are

complementary. They both require ___ hydrogen bonds.

Adenine thymine

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Cytosine guanine

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• __________ of bases determines the genetic information and is

unique to each organism.

• If the organisms are closely

related the more _______ the DNA nucleotide sequence

will be.

Sequence

alike

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• The rungs of the ladder can occur in any order (as long as

the ______________ is followed).

• If the order of base pairs in a

DNA molecule is changed what might occur?

base-pair rule

MUTATIONS!

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• DNA is made of a ________

strand of nucleotides.

• The DNA from each side is

________________ to the other

side.

double

complementary

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• If you know the sequence of one side

you can determine the sequence of

the other side.

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• What is the complementary strand to this DNA molecule?

A A T C G T A C C G A T

T T A G C A T G G C T A

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C. Two Functions of DNA

1. To direct and control

___________________.

2. _________________ = reproducing an exact

copy of DNA so that

the information can

be passed on during

cellular division.

protein synthesis

DNA replication

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D. DNA Replication

____________ is the process where DNA

makes a copy of itself.

Replication

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D. DNA Replication

_____________________________ = parental

strands of DNA separate, serve as a

template, and produce DNA molecules

that have one strand of parental DNA

and one strand of new DNA.

Semiconservative replication

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Semiconservative Replication

• Helps ________ the number copying errors.

• 3 stages: ___________, base pairing, and

joining.

reduce

unwinding

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Why does DNA need to replicate?

• Cells divide for an organism to grow

or reproduce; every new cell needs

a copy of the DNA or instructions to know how to be a cell.

• DNA replicates right

before a cell divides

___________. (MITOSIS)

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E. Replication Steps

1) Unwinding: DNA

helicase (an

_________) unwinds

and unzips the

double helix and

begins to break

the H bonds

between the

nitrogen bases.

enzyme

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E. Replication Steps

2) Base pairing: __________________ (an

enzyme) runs along the parent chain

of DNA in the 3’-5’ direction and bonds

free floating nucleotides to the parent

(original) chain - - based on base

pairing rules.

− The newly assembled strand is called a

________________ of nucleotides and

reforms the double helix.

− Each new strand is a _____________ of

parent strand.

DNA polymerase

leading strand

complement

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E. Replication Steps

3) Because DNA synthesis can only occur

5’ to 3’, a second type of

________________ binds to the other

template strand as the double helix

opens.

− DNA polymerase synthesizes discontinuous

segments of nucleotides (called

___________________).

DNA polymerase

Okazaki fragments

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E. Replication Steps

4) Joining: Another enzyme, _____________

then bonds these Okazaki fragments

together into the ________________.

DNA ligase

lagging strand

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E. Replication Steps

Therefore, the result is the formation of ___

DNA molecules, each of which is identical to

the original DNA molecule.

2

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DNA Replication

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F. What makes up our characteristics?

• If you have brown hair, what makes it

brown, as opposed to blonde, or

red?

• A pigment called

_________,

a _________, is

what you see as

“brown” in the

hair.

melanin

protein

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What makes you tall or short?

• The lengths of your bones are made

up of a framework of _______________. protein fibers

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So, if heredity material

controls our traits, and your traits are made of

proteins, then shouldn’t heredity material control the making of proteins?

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• This is exactly what _____ does!!

DNA

nitrogen bases

protein

• The order of

_________________

(A, T, C, G)

determines the

type of _________

that is

assembled.

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• If the order of bases is accidentally

changed, then _______________ occur

which can change the proteins that

need to be made.

mutations

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Radiation and Mutations

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III. Link between DNA & Proteins

• In the cytoplasm of each cell, there

are tiny organelles where proteins are

assembled. What are they called?

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• If a hair cell needs to

make melanin.

• How do the instructions to synthesize this protein get from the DNA to the ribosome?

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• Something must carry these instructions from the nucleus to the ribosomes in the cytoplasm. This “messenger” molecule is ________!! mRNA

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A. RNA: Ribonucleic Acid

Structure: DNA RNA

Strands of

nucleotides Double Single

Sugars Deoxyribose Ribose

Nitrogen

bases A, T, C, G A, U, C, G

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• Three kinds of RNA

1. ________

messenger RNA

mRNA

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• Structure: _________________

• Function: Carries the _____

message from the nucleus to

the ribosomes.

• _______ = set of three

nitrogen bases representing an amino acid

single stranded

DNA

Codon

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2. _______ transfer RNA tRNA

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tRNA • Structure: has an ___________ that is a

complement to the ______________ at

one end and an ______________ at the

other end.

anticodon

mRNA codon amino acid

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tRNA • Function: Carries the _____________ to

the ribosomes for protein production.

amino acids

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3. ______ ribosomal RNA

Structure: a part of ribosome

Function: Creates the ___________________ between

the amino acids during

protein production.

rRNA

peptide bonds

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The

molecule of

heredity 49

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IV. Protein Synthesis

Overview:

• The _________ created is

determined by the base

arrangement in DNA (code sequence)

protein

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_____ transfers this information to mRNA, which carries the code to the ribosome where tRNA decodes it. ______ anticodons base pair with mRNA’s codons. Then ______ forms peptide bonds between ____________ to form a _________.

DNA

tRNA

rRNA amino acids

protein 52

• The process of protein synthesis is broken down into

two sub-processes: transcription and translation.

1. ____________ = the process through which _____ transfers

the code to ______.

Takes place in the _________.

Transcription

DNA

mRNA

nucleus

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2. ____________ = the process through which

mRNA is decoded and forms a protein.

•Takes places at a __________

Translation

ribosome

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Transcription: from DNA to mRNA

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1. _________________ (enzyme)

attaches at a specific

location on DNA.

2. The enzyme then causes

the DNA strands to

separate from one another

and allow one of the DNA

strands to be __________.

RNA polymerase

decoded

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3. mRNA nucleotides are floating around in the nucleus to find their complement on the DNA strand and ______ together. This is possible due to the base-pairing rules.

4. Once the DNA segment has been copied by the mRNA bases, the mRNA strand separates from the DNA.

bond

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5. The mRNA (messenger RNA)

leaves the _________ through

a nuclear pore and enters

the ___________ → goes to

the ___________ for protein

synthesis.

6. DNA zips up again to create

the original double helix.

nucleus

cytoplasm

ribosomes

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Why is Transcription Important?

• It is needed to get the _______________ out of the

_________ so the ribosomes know what _________ to

make!

DNA message

nucleus

protein

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• Without transcription, the ribosome would have no

idea what proteins the body needed and would not

make any.

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You could _____ replace the hair that we lose every day;

could NOT grow long fingernails; be able to fight

off disease; cells would fall apart because the proteins

were not being __________!!

NOT

replaced

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Translation (Protein Synthesis) from RNA to Protein

1. First _______ of mRNA attaches to __________.

codon

ribosome

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2. _______ (transfer RNA) each carries a specific amino acid;

the tRNA anticodon will pair up with its complementary mRNA

codon.

tRNA

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3. When the 1st and 2nd amino acid is

in place, the rRNA joins them by

forming a ________________. As process continues, amino acid chain

is formed until a stop codon.

peptide bond

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4. The tRNA is __________ to find another of the

same amino acid so the process can occur

again and again.

5. The protein chains are

then transported to other areas of the body

that need them.

recycled

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Why is Translation Important?

• Makes all the __________ that the body need.

• Without translation, proteins would not be made and we could not replace the proteins that are depleted or damaged.

proteins

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Summary of Protein Synthesis

• Below you will find the base sequence of a single strand

of DNA. Please fill in the complementary bases of

mRNA, tRNA and the correct amino acid sequence.

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• NOTE: mRNA and tRNA never have ___ in the

sequence! Always use the _______ strand to code for

the ________________.

T’s

mRNA

amino acids

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DNA Code

T A C T T G C A T G G A A T G G T A A C G G T A A C T G

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DNA & mRNA

T A C T T G C A T G G A A T G G T A A C G G T A A C T G

A U G A A C G U A C C U U A C C A U U G C C A U U G A C

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DNA & mRNA & tRNA

T A C T T G C A T G G A A T G G T A A C G G T A A C T G

A U G A AC G U A C C U U A C C A U U GC C A U U GA C

U A C U U B C A U B B A A U B B U A A C B B U A A C U G

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Amino Acids

• Use the mRNA strand!

• AUG – methoinine (start)

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• AAC – asparagine

• GUA – valine

• CCU – proline

• UAC – tyrosine

• CAU – histidine

• UGC – cysteine

• CAU – histidine

• UGA - stop

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Mutations

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MUTATIONS

____________________________ Chromosomal Mutations

Translocation

Inversion Insertion/deletion

Nondisjunction

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MUTATIONS

____________________________ Gene Mutations

Frameshift

Base Insertion Base deletion

Point

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VOCABULARY:

• ____________ = a random error or change in DNA sequence that may affect whole chromosomes or just one gene.

Mutation

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VOCABULARY:

• ____________ = certain substances or conditions that can create a greater rate of mutation

Mutagen

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Mutagens:

• Examples:

–Some _________

–High temperatures

–______________

–Radiation

viruses

Chemicals

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Chromosomal Mutations:

• Changes in chromosomes,

usually during meiosis when

gametes are being made.

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Chromosomal Mutations:

1. ________________ = failure of

homologous chromosomes to

separate during meiosis

resulting in gametes(egg or

sperm) with too few or too many chromosomes.

Nondisjunction

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Chromosomal Mutations:

REMEMBER: Humans are

_________ creatures; meaning

for every chromosome in our

body, there is another one to

match it.

diploid

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Chromosomal Mutation:

____________ =

abnormal number of chromosomes.

Ex. Trisomy,

monosomy

Aneuploidy

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ANEUPLOIDY:

• ________ = zygote contains

three copies of the chromosome.

–Ex: Down

syndrome, Klinefelter’s

(XXY)

Trisomy

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ANEUPLOIDY:

• ____________ = zygote contains

only one chromosome of the pair

(it is missing one chromosome).

Monosomy

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Chromosomal Mutation:

2. _________ = occurs when part

of a chromosome is missing.

Deletion

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Chromosomal Mutation:

3. ______________ = occurs when part

of a chromatid breaks off and attaches to its sister chromatid. The

result is a duplication of genes on the

same chromosome.

Duplication

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Chromosomal Mutation:

4. ___________ = Segment of chromosome

breaks off and is reinserted backwards (will

flip upside down)

Inversion

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Chromosomal Mutation:

5. ________________ = occurs when

part of one chromosome breaks off and is added to a different

chromosome.

Translocation

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Gene Mutations:

Changes in DNA sequence that

will then change the amino

acid sequence. (Remember:

amino acids make up our

proteins!)

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Gene Mutations:

1. ________________ = a change

in a single base pair in DNA.

Point mutation

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Gene Mutations: 2. ______________

_____________ = error in the DNA sequence that adds or deletes a single nitrogen base, causing nearly all amino acids following the mutation to be changed.

Frameshift mutation

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Frameshift Mutation:

• ______________ =

One nitrogen base (A, T, C or G)

is deleted from

the DNA sequence.

Base deletion

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Frameshift Mutation:

• _______________ =

Extra nitrogen

base is added

to the DNA

sequence.

Base insertion

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Mutations

• DNA is constantly subject to mutations, accidental changes in its code.

• Mutations can lead to missing or malformed proteins, and that can lead to disease.

• However, few mutations are bad for you. In fact, some mutations can be beneficial. Over time, genetic mutations create genetic diversity, which keeps populations healthy. Many mutations have no effect at all. These are called silent mutations.

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Mutations: Can be bad but . . .

• Cyclops shark:

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Mutations: Not necessarily a bad thing

• The speckled moth:

Had a mutation that made them black and not speckled. They were easily seen by birds and eaten.

During industrial revolution trees were covered with soot. “Mutated” black moths survived.

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Mutations: Not necessarily a bad thing

• Sickle-Cell Anemia & Malaria:

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Mutations

• The mutations we hear about most often are the ones that cause disease.

• Some well-known inherited genetic disorders include cystic fibrosis, sickle cell anemia, Tay-Sachs disease, phenylketonuria and color-blindness, among many others.

• All of these disorders are caused by the mutation of a single gene.

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