DNA & RNA

Vocabulary you should know… DNA: (deoxyribonucleic acid) the

material that contains the information that determines inherited characteristics

Nucleotide: in a nucleic-acid chain, a sub-unit that consists of a sugar, a phosphate, & a nitrogenous base

More Vocab…

Nitrogenous base: an organic base that contains nitrogen, such as a purine or pyrimidine; a sub-unit of a nucleotide in DNA or RNA

Purine: a nitrogenous base that has a double-ring structure; one of two general categories of nitrogenous bases found in DNA & RNA; either adenine or guanine

More Vocab…

Pyrimidine:a nitrogenous base that has a single-ring structure; one of the two general categories of nitrogenous bases found in DNA& RNA; thymine, cytosine or uracil

Base-Pairing Rules: the rules stating that cytosine pairs w/ guanine & adenine pairs w/ thymine in DNA & adenine pairs w/ uracil in RNA

More Vocab…

Complementary Base Pair: the nucleotide bases in one strand of DNA or RNA that are paired w/ those of another strand; adenine pairs w/ thymine or uracil, and guanine pairs with cytosine

Base Sequence: the order of nitrogenous bases on a chain of DNA

Double Helix: shape of a DNA molecule formed when two twisted DNA strands are coiled into a springlike structure & held together by hydrogen bonds b/t the bases

DNA – deoxyribonucleic acid The genetic information for an

organism DNA contains the instructions that

cells need to make every protein required for essential life functions

Found mostly in the nucleus of cells

Composed of 100’s of 1000’s of repeating units of nucleotides

DNA Photographed through x-ray

crystallography by Rosalind Franklin in the 1950s (w/ help from Maurice Wilkins)

1st model was created by James Watson & Francis Crick in the ‘50s, with the use of Franklins x-ray crystallography picture

Rosalind Franklin

Maurice Wilkins

James Watson & Francis Crick

DNA Made of subunits called nucleotides:

1 phosphate group 1 deoxyribose – simple sugar **this is what DNA is named for

1 of 4 nitrogen basesEither purines or pyrimidines

NITROGEN BASES Purines: double ringed

structure Adenine (A) Guanine (G)

Nitrogenous Bases

Pyrimidines: single ringed structure Thymine (T) Cytosine (C)

STRUCTURE OF DNA Shape:

double helix – repeating units of nucleotides

**the sequence of nucleotides determines gene function

DOUBLE HELIX 2 chains of nucleotide monomers

running anti - parallel Phosphate groups make up the

backbone of the double helix Covalent bonds hold the

nucleotides together by connecting the deoxyribose of one nucleotide to the phosphate group of the adjacent nucleotide

Double Helix Cont’d

The nitrogen bases of the nucleotides pair up to link the 2 helixes

hydrogen bonds b/t the nitrogen bases hold the strands of the double helix together

Double Helix Structure

Base-Pairing Rules Adenine (A) & Thymine

(T) are always together Cytosine (C) & Guanine

(G) must then

pair together

DNA Basics Quiz

1. What is DNA?2. The first person to photograph DNA

was ____________.3. The first people to make a model of

DNA were ________ & ______.4. A strand of DNA is made up of

repeating units of __________.

DNA Basics Quiz Cont’d

5. A nucleotide is composed of 3 parts, name all three.

6. List the 4 different nitrogenous bases.

7. Which part of the nucleotide makes up the backbone of the strand of DNA?

DNA Basics Quiz Cont’d

8. What type of bonds hold the deoxyribose of one nucleotide to the phospate of the adjacent one?

9. What type of bonds hold the complementary nitrogenous bases together?

10.Out of Adenine, Guanine, Cytosine & Thymine, tell me the two complementary pairs.

DNA Technology

DNA is manipulated for many different reasons: Crime scene analysis Genetic counseling Research Treatment of disease

DNA Technology

DNA ID Only identical twins have identical

DNA Only 10% of the human genome

varies between all humans The 10% that differs falls on the

same chromosome region so we can isolate this DNA and use it to make important discoveries

Identifying DNA

Step 1: Copying DNA: Polymerase Chain Reaction Method of quickly copying DNA from

small samples Step 2: Cutting DNA: Restriction

Enzymes Restriction enzymes recognize specific

short DNA sequences & cut in or near them

This isolates the DNA needed for ID

Identifying DNA cont’d

Step 3: Sorting DNA by Size: Gel Electrophoresis Gel electrophoresis separates DNA

according to size and charge Does this by running an electrical current

through gel that the DNA cut by the restriction enzymes has been placed in, + & - charged pieces move to opposite ends

The resulting pattern is called the DNA fingerprint

Identifying DNA

Step 4: Comparing DNA: DNA Fingerprints Compare the DNA sample to other DNA

fingerprints until you find a match, or pattern that you are looking for

Accuracy?? The odds that 2 people will share the

same DNA fingerprint: 1: 100 billion # of people on Earth: approx 7 billion

Gel Electrophoresis

Recombinant DNA

Genetic engineering: the process of altering the genetic material of cells or organisms to allow them to make new substances

DNA recombination/Recombinant DNA: Joining together DNA from two different

organisms

DNA Recombination

Step 1: isolate the DNA and the plasmid of interest Plasmids: small rings of DNA found

naturally in some bacterial cells in addition to the main bacterial chromosome

Step 2: restriction enzymes cut the DNA into fragments

Step 3: fragments and plasmid DNA are joined together permanently by DNA ligase

DNA Recombination Cont’d

Step 4: recombinant DNA plasmids, each with different fragments of DNA, are inserted into bacterial cells These recombinant DNA plasmids are

then copied each time the bacterial cell copies its own DNA

Step 5: once a colony of bacterial cells containing the recombinant DNA plasmids is created, the recombinant DNA is removed to be used

Recombinant DNA

Central Dogma of Molecular Genetics How we go from DNA to RNA 1. replication (DNA copies itself) 2. transcription (DNA acts as a

template for the production of messenger RNA (mRNA))

3. translation (mRNA carries coded information to ribosomes; ribosomes "read" this information and use it to make proteins)

The Central Dogma Cont’d

Dogma Cont’d

Replication: Vocab you should know…

DNA replication: process by which DNA is copied in a cell before a cell divides by mitosis, meiosis or binary fission

Helicase: enzymes that separate DNA strands by breaking the hydrogen bonds that hold the nitrogenous bases together

Replication: More vocab… Replication Fork: a Y shaped point

that results when the two strands of DNA double helix separate so that the DNA molecule can be replicated

DNA Polymerase: an enzyme that catalyzes the formation of the DNA molecule

Replication: More Vocab… Semi-conservative Replicaiton: in

each new DNA double helix, one strand is from the original molecule & one strand is new

Mutation: a change in the nucleotide-base sequence of a gene or DNA molecule

Facts about Replication

Occurs during interphase of both the cell cycle for mitosis and for meiosis

Happens to all of the DNA in the cell, not just selected parts (every chromosome)

Replication (of DNA)1. Strands of DNA separate

a)Helicase enzymes move along the strand of DNA

b)They break the hydrogen bonds between the nitrogen bases

c) The two strands separate, exposing a a Y-shaped region called the replication fork

Replication: Helicase & the Replication Fork

Replication Cont’d

2. DNA polymerase enzymes add complementary nucleotides to the two separated strandsa) The nucleotides are found free-

floating around inside the nucleus

b) As the nucleotides are added, covalent bonds form b/t the deoxyribose of one and the phosphate of the next

Replication: Adding Nucleotides Cont’d

2. Adding nucleotides cont’dc) Hydrogen bonds are

formed b/t the nitrogenous bases from the original strand and the nitrogenous bases on the newly added nucleotides

Replication: Adding Nucleotides Cont’d

2. Adding Nucleotides cont’dd) DNA synthesis (creation) occurs in

different directions on each strandi. As the replication fork moves along

the original DNA, synthesis of one strand, the leading strand, follows the movement of the replication fork

ii. Synthesis of the other strand, the lagging strand, moves in the opposite direction, away from the replication fork

Replication: Adding Nucleotide Cont’d

2. Adding Nucleotides Cont’de) Because the nucleotides are added

to the leading and lagging strands in opposite directions, it leaves gaps in the newly synthesized DNA, called Okazaki Gaps

f) These gaps are later joined together by the enzyme DNA ligase

Replication: Leading & Lagging Strands

Replication Okazaki Fragments

Replication Cont’d

3. DNA polymerase enzymes finish replicating the DNA & fall off

The result of replication of a strand of DNA is two completely identical strands of DNA, each containing one old strand & one new stand = semiconservative replication

Semi-Conservative Replication

Replication cont’d

DNA replication flash interactive

DNA Replication Quiz

1. What are the three parts of the Central Dogma of molecular genetics?

2. What is the first thing that must happen in order for DNA to replicate itself?

3. What is the name of the enzyme that separates the two strands of DNA?

Replication Quiz Cont’d

4. Helicase breaks the ________ bonds that hold the nitrogenous bases together.

5. The Y-shaped region that appears as the two strands separate is called the ________ _______.

6. After the strands separate, what is the second thing that happens as DNA replicates itself?

Replication Quiz Cont’d

7. What is the name of the enzyme that adds the free-floating nucleotides to the two exposed strands of DNA?

8. The gaps created as the new DNA strands are being synthesized are called _________ __________.

Replication Quiz Cont’d

9. What happens to the DNA polymerase after is finished being replicated?

10.Replication results in _____ (#) strands of DNA, each having one ____ strand and one _______ strand.

RNA: Vocabulary You Should Know Ribonucleic Acid (RNA): a natural polymer that is

present in all living cells & that plays a role in protein synthesis

Transcription: the process of forming a nucleic acid by using another molecule as a template; particularly the process of synthesizing RNA by using one strand of a DNA molecule as a template

Translation: the portion of protein synthesis that takes place at ribosomes & that uses the codons in mRNA molecules to specify the sequence of amino acids in ploypeptide chains

RNA: move vocab…

Protein Synthesis: the formation of proteins by using infomration contained in DNA & carried by mRNA

Ribose: a five-carbon sugar present in RNA Messenger RNA (mRNA): a single-stranded

RNA molecule that encodes the information to make a protein

RNA: more vocab…

Ribosomal RNA (rRNA): an organelle that contains most of the RNA in the cell & that is responsible for ribosome function

Transfer RNA (tRNA): an RNA molecule that transfers amino acids to the growing end of a polypeptide chain during translation

RNA Polymerase: an enzyme that starts (catalyzes) the formation of RNA by using a strand of DNA molecule as a template

RNA: More vocab…

Promoter: a nucleotide sequence on a DNA molecule to which an RNA polymerase molecule binds, which initiates the transcription of a specific gene

Termination Signal: a specific sequence of nucleotides that marks the end of a gene

Genetic Code: the rule that describes how a sequence of nucleotides, read in groups of three consecutive nucleotides (triplets) that correspond to specific amino acids, specifies the amino acid sequence of a protein

RNA: More Vocab…

Codon: in DNA, a three-nucleotide sequence that encodes an amino acid or signifies a start signal or a stop signal

Anticodon: a region of tRNA that consists of three bases complementary to the codon of mRNA

Genome: the complete genetic material contained in an individual

RNA – Ribonucleic Acid

RNA: Structure & Comparison to DNA RNA

1. Single stranded2. Sugar = ribose3. Nitrogenous

bases:1.Adenine2.Cytosine3.Guanine4.Uracil

4. Usually much shorter

DNA1. Double stranded2. Sugar =

deoxyribose3. Bases:

1.Adenine2.Cytosine3.Guanine4.Thymine

4. Usually much longer: 100s or 1000s of genes

RNA v. DNA

RNA: Types of

1. mRNA: messenger RNA Single stranded carries instruction from a

gene to make a protein Eukaryotic cells: carries

messages from DNA in the nucleus to a ribosome in the cell’s cytoplasm

mRNA

RNA: Types of …

2. tRNA: transfer RNA transports amino acids to

the ribosomes (rRNA) to be assembled into proteins

Made of many nucleotides linked together

tRNA

RNA: Types of …

3. rRNA: ribosomal RNA This type of RNA makes up a part

of ribosomes Ribosomes are organelles in each

cell where protein synthesis occures

clamp onto the mRNA & use its info to assemble amino acids in the correct order to make proteins

rRNA

COMPOSITION OF RNA

Made of nucleotides: 1 phosphate group 1 ribose – type of sugar 1 of 4 nitrogen bases

RNA’s NITROGEN BASES

Purines: Adenine (A) Guanine (G)

Pyrimidines: Cytosine (C) Uracil (U) ***instead of Thymine

RNA Base-Pairing Rules

Adenine pairs w/ Uracil (because there is no thymine)

Cytosine pairs w/ Guanine

RNA Base-Pairing

RNA Quiz

1. Protein synthesis results in the creation of ________.

2. RNA has _______ strands.3. RNA has the sugar _________.4. Name the 4 bases for RNA.5. RNA is usually ______ than DNA.6. Name the 3 types of RNA.7. What does mRNA do?

RNA Quiz Cont’d

8. What does tRNA do?9. rRNA is found on what cell part?10.What are the base-pairing rules for

RNA?

Transcription

The rewriting of genetic instructions from DNA into RNA

“transcribes” DNA into genes Takes place in the nucleus of

eukaryotic cells Takes place in the cytoplasm

of prokaryotic cells

Transcription Steps

1. Unwinding & separating the DNA strands The enzyme RNA

polymerase binds to a promoter (a specific codon that starts transcription) on the DNA molecule

DNA unwinds & separates

Transcription Steps: Unwinding & Separating DNA

Transcription Steps

2. Adding RNA nucleotides to create a strand of RNA RNA polymerase adds free-floating

RNA nucleotides to one of the exposed DNA strands

The nucleotides that are added are complementary to one of the DNA strands

Only a specific section of the DNA strand is used to create the strand of RNA

Adding RNA Nucleotides

Transcription Steps

3. Release of the RNA molecule RNA polymerase reaches a

termination signal that tells it to stop RNA polymerase releases both the

DNA & the newly formed RNA molecule

RNA created is mRNA The RNA molecule is free to perform

its “job” RNA polymerase is available to

transcribe more genes

Releasing both DNA & RNA

Transcription Quiz

1. Transcription rewrites what?2. Where does transcription take place

in eukaryotic cells?3. What is the 1st step in transcription?4. What is the enzyme that unwinds &

separates DNA?

Transcription Quiz Cont’d5. What is the second step of

transcription?6. What are added to the exposed

strand of DNA?7. What tells RNA polymerase when to

stop adding nucleotides?8. The newly formed RNA is __RNA.

Transcription Quiz Cont’d9. When RNA polymerase reaches the

terminal signal it releases both _______ & _______.

10.What does RNA polymerase do after it releases the DNA & newly formed RNA molecule?

Protein Synthesis Gene: segment of DNA ,

located on a chromosome that codes for a hereditary characteristic (like hair color)

Genes direct the synthesis or making of proteins for that particular trait

Genes use RNA to help make the appropriate proteins

Protein Synthesis

Genetic information flows in the following order: Transcription Translation / Protein synthesis

DNA → RNA → protein Proteins are important b/c they create &

do everything that our body is & does

The Genetic Code

The code needed to convert the language of mRNA into proteins

Proteins are made of amino acids Amino acids are made based on the

nucleotide sequence in mRNA 3 adjacent nucleotides in mRNA

specify a particular amino acid The 3 nucleotide sequence that

encodes an amino acid, a start signal or a stop signal = a codon

Codons

Codons can only code for one amino acid i.e.: UUA = Leucine and only leucine

Each amino acid can be coded for by more than one codon the amino acid leucine can be coded for

by all of the following codons i.e.: UUA = Leucine, UUG = Leucine CUU = Leucine, CUC = Leucine CUA = Leucine, CUG = Leucine

Codons Cont’d

Start codons: sequence of nucleotides in mRNA that signals where translation should begin Codes for the amino acid methionine

Stop codons: sequence of nucleotides in mRNA that signals where translation should stop Does not code for any amino acid

Codons in mRNA

Proteins

Made of polypeptides Polypeptides are chains of amino acids

linked by peptide bonds 20 different amino acids Polypeptide chains are 100s of 1000s of

amino acids long The sequence of amino acids determine how

the protein will fold & twist into a 3d shape, the shape gives the protein its function

Proteins

Translation

Is the synthesis or making of a protein

The instructions for making a protein are transcripted from DNA into mRNA

All three types of RNA are involved in translation

Translation Steps

1. Joining RNAs rRNAs & tRNAs attach to a mRNA Enzymes attach an amino acid to one

end of each tRNA The other end of the tRNA contains the

anticodon for mRNA A tRNA carrying the amino acid

methionine must be present to start the reading of mRNA & attaches to a start codon on mRNA

T-RNA

Translation

Translation Steps Cont’d

2. Creation of a polypeptide chain tRNAs carrying correct amino acids, pair their

anticodons w/ the codons on the mRNA strand Methionine detaches from the 1st tRNA after the

2nd anticodon is added A peptide bond forms b/t methionine & the 2nd

amino acid to start a polypeptide chain The 1st tRNA exits the ribosome Ribosome moves one codon down on the mRNA

strand

Translation

Translation Step Cont’d

3. Polypeptide Chains Grow mRNA continues to move through the

ribosome New tRNAs w/ correct anticodons move

in & peptide bonds are created b/t the amino acids of each tRNA

The polypeptide chain moves from one tRNA to the next tRNA & attaches to its amino acid

Translation

Translation Steps

4. Stop Codon Polypeptide grows one amino acid at a

time until it reaches a stop codon Polypeptide falls off

Translation

Translation Steps Cont’d

5. End of Translation All the parts that are needed for

translation come apart The last tRNA exits the ribosome The ribosome moves away from the

mRNA All the parts are free to be used over &

over again

Translation

Translation Quiz

1. Proteins are made of ____ ____, which are made of 3 RNA ______.

2. Polypeptides are chains of amino acids linked by _____ ____.

3. Translation is the synthesis of ________.

4. List the types of RNA involved in protein synthesis.

Translation Quiz Cont’d

5. The first tRNA to be used during translation must carry the amino acid ________.

6. A polypeptide chain is started when methionine is bonded to the __________.

7. For the polypeptide chain to grow the mRNA must ____________.

Translation Quiz Cont’d

8. The polypeptide chain stops growing when it reaches the ______ ________.

9. When the polypeptide chain reaches the stop codon what happens to the chain?

10.Once the polypeptide chain falls off, what happens to all the parts that assembled to translate RNA?