DNA, Protein Synthesis and Biotechnology EOC Review

3.1.1 Explain the double-stranded, complementary nature of DNA as related to its function in the cell.

3.1.2 Explain how DNA and RNA code for proteins and determine traits.

3.1.3 Explain how mutations in DNA that result from interactions with the environment (i.e. radiation and chemicals) or new combinations in existing genes lead to changes in function and phenotype.

3.3.1 Interpret how DNA is used for comparison and identification of organisms.

3.3.2 Summarize how transgenic organisms are engineered to benefit society.

3.3.3 Evaluate some of the ethical issues surrounding the use of DNA technology (including cloning, genetically modified organisms, stem cell research, and Human Genome Project)

Hydrogen bonds

Nucleotide

Sugar-phosphate backbone

KeyAdenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

DNA Structure…What do you remember?

Deoxyribose

•DNA: Deoxyribonucleic Acid•2 long chains of nucleotides•Joined together in the form of a ladder •Ladder is twisted in the form of a double helix or spiral•Adenine pairs with Thymine•Guanine pairs with Cytosine

What Is the “Ladder”?

Quick Check1. Describe the structure of DNA2. Draw and label a nucleotide3. Identify the complementary base pairs for the

following nitrogenous bases: ATG CTG CGA

DNA Replication•During cell division a copy of DNA must be made during Interphase through the process of Replication.•When new cells are formed each new cell gets an exact copy of the genetic information.

Steps of Replication•During replication, each strand serves as a pattern to make new DNA molecule.

1. The 2 nucleotide strands separate at base pairs. • They unzip like a zipper using DNA

Helicase (enzyme)2. Each strand then builds its opposite strand

by base pairing with nucleotides that float freely in the nucleus.

3. Each new DNA molecule has 1 nucleotide strand from the original DNA molecule and 1 nucleotide strand made from free nucleotides in the nucleus. We call this semi-conservative.

4. The strands are zipped up and proofread for mutations (mistakes).

Quick Check

1. When and why does DNA replication occur?2. Describe the steps of DNA replication.

RNA

▪ RNA: ribonucleic acid

▪ Carries out protein synthesis

▪ Differences from DNA:

▪different sugar (ribose)▪single strand▪different base-URACIL instead of

thymine

3 Types of RNA:

• Messenger RNA: (mRNA) carries nucleotide sequence from nucleus to ribosome in transcription.

• Transfer RNA: (tRNA) picks up amino acid in cytoplasm and carries them to ribosome in translation.

• Ribosomal RNA: (rRNA)found in ribosome, joins mRNA and tRNA; forms protein in translation.

-messenger RNA

DNA RNA

Quick Check: Compare and contrast DNA and RNA

The genetic information that is

passed from a parent to its offspring is

found in DNA molecules. Segments

of DNA known as genes code for the

production of proteins. These

proteins cause specific traits to be

expressed.

Protein Synthesis

Rap

mRNADNA

RNAPolymerase

TranscriptionAdenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

Quick Check:What is the product of

Transcription?

mRNA Start codon

Ribosome

Methionine

PhenylalaninetRNA

Lysine

Nucleus

Translation

mRNA

Quick Check:Where does Translation

occur?

Translation• Conversion of RNA into amino acid sequence that makes a protein• The mRNA leaves the nucleus and enters the cytoplasm• Ribosomes attach to mRNA• tRNA (carrying anti-codon) picks up the correct amino acids and

carries them to the mRNA strand forming the proteinEx: tRNA carries GAU (anti-codon)& looks for CUA on mRNA

Quick Check: Label the following

C.

D.

E.

F.

B. A.

A.

Process 1 _________________

Process 2 _________________

What polypeptide would be determined by a gene with the base sequence AAGGATCCG?

What polypeptide would be coded by the following set of nucleotides?TCATATAGCGCAACA

What polypeptide would be coded by the following set of codons? AUGCCUACGUGGGAC

Quick Check:Synthesize the proteins!

Gene mutations result when one or more base pairs are inserted, deleted, or substituted in an organism's DNA sequence and are not repaired by an organism's enzymes. They may harm, benefit, or have no effect at all on an organism and/or the organism's offspring.

Mutations that occur in somatic cells can only be passed on to the daughter cells of the mutant cell. Cancer is a disease that results when mutations occur in an organism's body cells.Mutations that occur in an organism's gametes can be passed on to the organism's offspring.

Quick Check:Would a negative

mutation in a skin cell be heritable? Why or

why not?

DNA Fingerprinting

Quick Check:How are the DNA segments

organized in a DNA fingerprint?

The Human Genome Project (HGP) was a 13 year research project to sequence all the base pairs that compose human DNA.Scientists produced a gene map which showed the relative location of each known gene on every human chromosome. The gene map also showed the DNA sequences of all the human genes which is used in biotechnology applications.

Quick Check:What was the purpose of

the Human Genome Project?

Genetic engineering involves taking genes (identified by

HGP) from one organism and placing them into another in

order to express desired trait.

Applications of Genetic Engineering include:✹In medicine, genetic engineering is used to mass produce hormones, such as insulin and human growth hormone as well as vaccines.✹In agriculture, genetic engineering is used to create genetically modified organisms, such as crop plants that are more resistant to disease.

✹Gene therapy: specific genes are inserted into an individual's cells (using virus) to

replace a defective or mutant allele.

Quick Check:Describe the process and 2

applications of Genetic Engineering

Since stem cells have the potential to become

any type of cell, scientists hope that by

injecting or transplanting stem cells into diseased or damaged tissue, the

stem cells (primarily embryonic) can replace

abnormal or missing cells. 

Other Biotechnologies

Cloning

Quick Check:What are some possible

ethical issues of stem cell research and cloning?