DNA CoMpEtiTiOnCome up with a team name that’s DNA-

related (ish)

Team with the most points gets a special prize! (Class with most overall points

also gets a prize)

DNA – Deoxyribonucleic AcidDNA is made up of repeating…Nucleotides – has 3 components:1.Phosphate Group2.Sugar – Deoxyribose 3. Nitrogen Base

Thymine always goes across from AdenineGuanine always goes across from Cytosine

**The part that carries the code is the base sequence

Covalent bond – connects nucleotides in a strand

Hydrogen bonds – they connect the 2 strands together

Forms shape of DNA – DOUBLE HELIX

A T

T A

C G

G C

G C

G C

• Chargaff’s Rule: [A]=[T] and [C]=[G]

• X-Ray diffraction pictures helped solve the structure of DNA’s double helix

• Finalized the structure of DNA and built the first ever DNA model

DNA is shaped like a double helix (a twisted ladder)

This shape was discovered by two scientists: James Watson & Francis Crick (Impossible without Rosalind

Franklin’s X-Ray diffraction photo of DNA!)

In general, DNA is replicated by 1. Uncoiling of the helix

2. Separating the strands (breaking the hydrogen bonds between base pairs)

3. Synthesizing two new strands by complementary base pairing

DNA replication begins at 1 point, called the “origin” and proceeds in 2 directions (bidirectional)

Hydrogen bonds break, two strands separate, 2 new strands are added to the old strands

DNA Replication – - DNA makes a copy of itself- Important during meiosis & mitosis – DNA gets passed on to daughter cells

• DNA polymerase adds nucleotides to the parent strands and checks the strand for errors

• Each double helix now has 1 old strand & 1 new strand•This is called SEMI-CONSERVATIVE• If the original strand of DNA is ATTGCACT, what is the complementary strand…?

• The tips of chromosomes are called telomeres

• Genes are not found in this region of the chromosome

•These areas are difficult to replicate, so an enzyme – telomerase – adds short, repeated sequences to the ends

1. Label ONE strand of your DNA with ANY sequence of your choosing

2. Label the opposite strand, following the base-pair rules (A – T, C – G)

3. What’s the 1st step in DNA replication

- The DNA “unzips” – crease your paper and “unzip” your DNA

4. What’s the 2nd step in DNA replication?

- DNA Polymerase adds nucleotides

- Lay your strands about 2” apart on a piece of paper

- Next to each original strand, write the NEW complementary DNA sequence

- You should now have 2 identical double-stranded molecules of DNA…yes?

DNA holds the directions for protein synthesis

Protein synthesis is the making of proteins

A gene is a sequence of DNA that carries the code for making one protein

Everything in you is made of or by proteins!

Protein Examples

Hemoglobin is a protein in your blood that transports oxygen

Collagen is a proteins that makes your cartilage and tendons

Keratin is a protein that makes up your hair & fingernails

Enzymes are proteins

RNA – Ribonucleic Acid

RNA is like DNA except…

* It is single stranded

* It has uracil instead of thymine

* It has ribose instead of deoxyribose

Nitrogen Bases

Sugars

&

Phosphates

RNA DNA

Types of RNA

1. mRNA – “messenger” RNA- Carries copies of instructions from DNA for

making amino acids into proteins

2. tRNA – “transfer” RNA- Transfers each amino acid to the ribosome as

specified by the code on mRNA

3. rRNA – “ribosomal” RNA- Makes up part of the ribosome, where

proteins are made

• Both DNA and RNA are involved in protein synthesis

2 parts of protein synthesis:1. Transcription – DNA is converted to RNA

- Occurs in the nucleus

2. Translation – RNA is converted to a protein

- Occurs in the cytoplasm

• Transcription (the 1st part of Protein Synthesis)

• Converts DNA to RNA

• DNA (in the nucleus) needs to send a code to the ribosome (in the cytoplasm)

• Problem: DNA can’t fit through the nuclear pores

• A special “messenger” is used to copy and carry the code…

Transcription

• messenger RNA (mRNA) goes into the nucleus and copies the DNA

• Uses enzyme – RNA Polymerase

• The next step is that mRNA moves from the nucleus to the cytoplasm and to the ribosome

• RNA has 1 different base pair!

DNA – ATCG

mRNA – UAGC

Translation (the 2nd part of Protein Synthesis)

• Translation – a process that converts mRNA into a protein

• Occurs on the ribosome in the cytoplasm of a cell

• ______________ - building blocks of proteins; join together into long chains called polypeptides

• ____________ - a sequence of 3 bases on mRNA that codes for a single amino acid

• _____________ – sequence of 3 bases on tRNA that is complementary to one mRNA codon

“UCU” is the codon that makes an amino acid called SERINE

Amino acids

Codon

Anticodon

•The tRNA lines up with 3 bases in mRNA (codon)

•tRNA anticodon GAA

•mRNA codon CUU

• Another form of RNA called transfer RNA (tRNA) carries amino acids to the ribosome and matches them to the coded mRNA message

mRNA attaches to the ribosome

•tRNA drops off the amino acid in the correct spot

Any change in the DNA structure (specifically the order of nitrogen bases) is a mutation.

Mutations can be helpful, harmful, or neutral.

Helpful – can create diversity in a population

Harmful – can cause things like cancer

Neutral – can have absolutely no effect at all

A mutagen is something that causes mutations in the DNA (for example: smoking, radiation from the sun etc)

Slooze Worm

An insertion mutation is when a nitrogen base is added to the existing DNA

A deletion mutation is when a nitrogen base is subtracted from the DNA

A substitution mutation is when one nitrogen base is put in place of another.

If our DNA was AATTGGCC

An insertion would be AATTAGGCC

A deletion would be AATGGCC

A substitution would be AAATGGCC

Gene Sequencing – Determining the order of nucleotide bases within a gene

DNA Fingerprinting – technique used in criminal investigations. DNA Fingerprinting takes the DNA out of a cell and separates it. This will allow investigators to distinguish body cells of different individuals (since they are unlikely to have the same DNA)

Cloning – take the DNA out of one of your cells then take the DNA out of a zygote (fertilized egg). Put the DNA from your cell into the zygote.

Genetic engineering is the process of moving genes from the chromosomes of one organism to those of another organism.

Recombinant DNA is formed by joining DNA

molecules.from two different organisms

What would represent the strand of DNA from which the mRNA strand in the diagram was made?

A.CUCAAGUGCUUCB.GAGUUCACGAAGC.GAGTTCACGAAGD.AGACCTGTAGGA

What is the amino acid sequence in the portion of the protein molecule coded for by the piece of mRNA shown in the diagram?

A. Ser-Tyr-Arg-GlyB.Leu-Lys-Cys-PheC.Val-Asp-Pro-HisD.Pro-Glu-Leu-Val