Chapter 10 Review Sheets - Biochemistry of the Genome

What did Gregor Mendel work with instead of DNA?

Why did he not work with DNA itself?

What form of science did his experiments lay the groundwork for?

Gregor Mendel worked with Garden Peas

He did not work with DNA because he did not know what it was

His experiments laid the groundwork for the science of Inheritance

What was the experiment performed by Frederick Griffith?

What is the Transforming Principle?

Is this an example of Vertical Gene Transfer?

* See picture.

Griffith’s Transforming Principle was that a non-pathogenic strain of a bacteria was able to “transform” into a pathogenic strain.

No, this experiment was an example of Horizontal Gene Transfer

Nucleic acids are _______, which means they are made up of many monomers. What is the monomer of nucleic acids?

Polymers

The monomer of nucleic acids is called a Nucleotide

What are the three components of a Nucleotide?

The three components are:

1. A Phosphate group (attached to 5’ carbon)

2. A Sugar molecule (deoxyribose in DNA, ribose in RNA)

3. Nitrogenous Base (Adenine, Guanine, Cytosine, Thymine, or Uracil)

What is the certain order of the nucleotides in the DNA of a cell referred to as?

The Base Sequence

Which carbon is the Phosphate Group attached to in a single nucleotide?

Which carbon does the Phosphate group attach to when covalently attaching to other nucleic acids?

ThePhosphate group in a single nucleotide attaches to the 5’ Carbon

When forming a nucleic acid strand, the Phosphate Group attaches to the OH group on the 3’ carbon of the other nucleic acid

List the five Nitrogenous Bases. Which are purines and which are pyrimidines?

Purines:

• Adenine

• Guanine

Pyrimidines:

• Cytosine

• Thymine (DNA)

• Uracil (RNA)

What is the special name for the covalent bond formed via dehydration between two nucleic acids?

Phosphodiester Bond

What are the complementary base pairs?

How many Hydrogen bonds are there between each pair?

(Purine - Pyrimidine)

Adenine - Thymine / Uracil —> Two Hydrogen Bonds

Guanine - Cytosine —> Three Hydrogen Bonds

What is the significance of complementary base pairing?

Allows for us to make a complementary copy of a DNA strand

What two types of bonds can take place in DNA that were identified in class?

The two bond types are:

1. Covalent Bonding

2. Hydrogen Bonding

What is the relative strength of the two bonds that take place in DNA?

Hydrogen Bonding < < < Covalent Bonding in strength

(Inter- MF is weaker than Intra- MF)

If heat is applied to DNA, what happens to the molecule?

The Hydrogen bonds break apart and the double-stranded helix begins to denature into single-stranded DNA

Describe the contributions of the following individuals:

Rosalind Franklin / Maurice Wilkins

Erwin Chargaff

Watson / Crick

Rosalind Franklin / Maurice Wilkins

• Used X-Ray Differentiation to take photos of DNA displaying its double-helix structure

Erwin Chargaff

• Found that in the base composition, A = T and C = G; Chargaff’s Rule

Watson / Crick

• Put together the previous two findings and proposed the structure of DNA as being Double-Helical

What is the overall charge of DNA?

Negatively Charged

What is the function of DNA?

DNA stores the information needed to build and control the cell

How are DNA and RNA similar? How are they different? Compare these factors:

Monomer

Sugar Component of the Nucleotide

Nitrogen Containing Bases

Complementary Base Pairs

Single or Double Stranded

Relative Length

Relative Stability

RNA:

• Monomer —> Nucleotides

• Sugar Component —> Ribose

• Nitrogen Bases —> A, G, C, U

• Base Pairs —> A - U and G - C

• Usually Single-Stranded

• Short (linear)

• Less Stable

DNA:

• Monomer —> Nucleotides

• Sugar Component —> Deoxyribose

• Nitrogen Bases —> A, G, C, T

• Base Pairs —> A - T, G - C

• Usually Double-Stranded

• Long (linear or circular)

• More Stable

What are the functions of RNA?

Four main functions:

1. Structural RNA

2. Informational

3. Catalyst (Ribozymes)

4. Synthesis

Which process involves the three major types of RNA?

Protein Synthesis

Briefly describe the function of the three types of RNA

mRNA (Messenger) —> provides a template for protein synthesis during translation

rRNA (Ribosomal) —> structural and catalytic (Peptidyl transferase activity)

tRNA (Transfer) —> brings Amino acids and reads the genetic code during translation

What is a gene?

A gene is a distinct unit of DNA that codes for proteins or functional RNA

What does it mean if a gene is said to be transcribed “constitutively”?

“Constitutively” means that the gene is being transcribed at all times

What does it mean if a gene is either upregulated or downregulated?

Upregulated —> Gene is being transcribed (On)

Downregulated —> Gene is NOT being transcribed (Off)

Define the terms Genotype and Phenotype

Which of the two can change and which stays the same?

Genotype —> full collection of genes a cell contains in its genome

Phenotype —> observable characteristics expressed by genes / genotype

Phenotypes can change, while Genotypes remain the same / constant

Compare the structures of Eukaryotic and Prokaryotic chromosomes using:

How many and what shape

How many copies

Supercoil or No Supercoil

Enzymes

Histones or No Histones

Eukaryotes:

• How Many & What Shape —> Multiple, linear chromosomes

• How Many Copies —> Diploid (two copies)

• Supercoiled

• Topoisomerase

• Has Histones

Prokaryotes:

• How Many & What Shape —> Single, circular chromosome

• How Many Copies —> Haploid (one copy)

• Supercoiled

• Topoisomerase (Unique, DNA Gyrase)

  • No Histones

How is DNA, which is relatively large, able to be stored in the cell?

What is the function of Topoisomerases in this process?

DNA supercoils on itself inside the cell at ~10 bp / turn

Topoisomerases facilitate the supercoiling process

What is noncoding DNA?

How does the amount of noncoding DNA differ between Eukaryotes and Prokaryotes?

Noncoding DNA is DNA that does not code for proteins or stable structural RNA

Noncoding DNA is much more abundant in Eukaryotic Cells

Is noncoding DNA important or is it just “junk”?

Noncoding DNA is not junk; it can serve a regulatory role during transcription

What are Plasmids?

How are they transferred between organisms?

What types of genes might be found on a Plasmid?

Plasmids are smaller loops of DNA that may contain one or a few genes that are not essential for normal growth

They are transferred between organisms via Horizontal Gene Transfer

Genes that provide organisms with a competitive advantage may be found on a Plasmid

How does the size of chromosomes vary amongst organisms?

Is the complexity of an organism directly related to the size of the chromosome?

Size of chromosomes vary greatly amongst organisms

The complexity of an organism is NOT related to the size of the chromosome