A1.2 Nucleic Acids

Why are viruses not considered to be alive?

Although they have genetic material (DNA or RNA), they do not have cells which carry out metabolism and homeostasis. They cannot respond to stimuli or grow. They cannot reproduce themselves.

What feature of the genetic code gives us confidence that modern life traces back to a single ancestor?

The genetic code is universal; the same codons (three mRNA nucleotides) code for the same amino acids in all organisms.*exception: mitochondria

The enzymes involved in DNA replication and transcription can only add nucleotides in the _' to _' direction

The enzymes involved in DNA replication and transcription can only add nucleotides in the 5' to 3' directionThe C-5 of a nucleotide is added to the C-3 end of the preceding nucleotide

The ______ Hypothesis statated that DNA was made of repeating units of T, A, C, & G. If the hypothesis is correct, there should be ___ quantities of the 4 nitrogen bases

The Tetranucleotide Hypothesis statated that DNA was made of repeating units of T, A, C, & G. If the hypothesis is correct, there should be equal quantities of the 4 nitrogen bases*This hypothesis was incorrect

Sugar-phosphate bonds form via a series of ____ reactions and release ____

Sugar-phosphate bonds form via a series of condensation reactions and release H2O

Sketch Ribose and Deoxyribose. Number the carbons.

Recall the central dogma of molecular biology

Nucleosomes consist of ___ charged DNA wrapped ___ times around a core of __ ____ charged histone proteins

Nucleosomes consist of negatively charged DNA wrapped two times around a core of 8 positively charged histone proteins. An additional linker histone protein holds the nucleosome together

Involved in supercoiling DNA and controlling gene expression

Name the characteristics of life (7)

All living organisms:

- Have at least one cell

- Are capable of carrying out metabolism

- Maintain homeostasis

- Respond to stimuli

- Are capable of reproduction

- Grow and develop

- Contain genetic information (in the form of DNA)

List the steps and findings of the Hershey-Chase Experiment

1. label phage protein with radioactive sulfur and phage DNA with radioactive phosphorus

2. Infect E. coli bacteria with phages

3. Blend to shear off empty protein coats from bacteria

4. Centrifuge, creating bacterial cell pellet and phage coats in supernatant

5. Findings: pellet contained radioactive phosphorus (DNA entered bacterial cells); supernatant contained radioactive sulfur (proteins remained outside)

6. Conclusion: DNA, not protein, is the genetic material

In their experiment, Hershey and Chase used radioactive ____ for the protein and radioactive ____ for the DNA.

In their experiment, Hershey and Chase used radioactive sulfur for the protein and radioactive phosphate for the DNA.

Identify and label the 5' and 3' ends on a DNA or RNA diagram.

The 5′ and 3′ designations refer to the number of the carbon atom in a deoxyribose sugar molecule. The 5′ end is identified by the presence of the phosphate group and the 3′ end is identified as ending in the pentose sugar (ribose or deoxyribose).In DNA, one strand will run from 5′ to 3′ and the complementary strand will run anti-parallel, from 3′ to 5′.

Hershey-Chase ExperimentThe pellet contained ____, showing that ____ entered the bacterial cells. The supernatant contained ____, showing that _____ remained outside.

Hershey-Chase ExperimentThe pellet contained radioactive phosphorus, showing that DNA entered the bacterial cells.The supernatant contained radioactive sulfur, showing that proteins remained outside.

Explain the role of falsifiability in determining the structure and function of DNA.

To falsify means that a statement, theory or hypothesis is proven to be wrong.Because he found that the amount of one base wasn't equal to the amount of the three other bases, Chargaff's data falsified the earlier hypothesis that DNA had a tetranucleotide structure.

Draw the basic structure of RNA

Draw the basic components of a nucleotide

DNA is a ___ helix made of two ____ strands of nucleotides

DNA is a double helix made of two antiparallel strands of nucleotides

Describe viruses in 3 words

obligate intracellular parasites

Complementarity of bases is based on _____

Hydrogen bonding

Compare and contrast the structures of purines and pyrimidines.

Both purines and pyrimidines are nitrogenous bases of DNA and RNA.

Pyrimidine: single ring nitrogenous bases

Cytosine

Thymine

Uracil

Purine: double ring nitrogenous bases

Guanine

Adenine

A ____ is a virus that infects bacteria

A bacteriophage is a virus that infects bacteria

_____-bonding makes a continuous chain of covalently bonded atoms in each strand of DNA or RNA nucleotides, which forms a strong "backbone" in the molecule

Sugar-phosphate bonding makes a continuous chain of covalently bonded atoms in each strand of DNA or RNA nucleotides, which forms a strong "backbone" in the molecule

_____ is the genetic material of all living organisms

Deoxyribonucleic acid (DNA) is the genetic material of all living organisms

____, ____, & ____ are nitrogen bases found in both RNA and DNA.adenine, cytosine & guanine are nitrogen bases found in both RNA and DNA.

adenine, cytosine & guanine are nitrogen bases found in both RNA and DNA.

____'s rule states that in any sample of DNA, the amount of guanine equals the amount of cytosine, and the amount of adenine equals the amount of thymine.

Chargaff's rule states that in any sample of DNA, the amount of guanine equals the amount of cytosine, and the amount of adenine equals the amount of thymine.

____ is the production of polypeptides by ribosomes using mRNA genetic code. The ribosome moves along the mRNA molecule in a _____ direction.

Translation is the production of polypeptides by ribosomes using mRNA genetic code. The ribosome moves along the mRNA molecule in a 5' to 3' direction.

____ is a nitrogen base in RNA but not in DNA. It forms hydrogen bonds to ____

uracil; adenine

____ is a nitrogen base in DNA but not in RNA. It forms hydrogen bonds to ____

Thymine; Adenine

Mnemonic for complementary bases: Apple - (Under) TreeCar - Garage

____ are the monomers of nucleic acids (DNA/RNA)____ are the monomers of proteins

Nucleotides are the monomers of nucleic acids (DNA/RNA)Amino Acids are the monomers of proteins

____ are sequences of DNA, and code for specific proteins.

Genes are sequences of DNA, and code for specific proteins

Their sequence of nitrogen bases determine the amino acid sequence in a protein.

____ are long DNA molecules which contain genes. Humans usually have ___ pairs

Chromosomes are long DNA molecules which contain genes. Humans usually have 23 pairs

(23 pairs in each cell, with the exception of gametes)

____ and ____'s experiment convinced the scientific community that DNA is the genetic material.

Hershey and Chase's experiment convinced the scientific community that DNA is the genetic material.

____ and ____ discovered the structure of DNA

Watson and Crick discovered the structure of DNA(using Franklin's work)

____ and ____ are purines.____, ____, and ____ are pyrimidines.

Adenine and Guanine are purines.

Cytosine, Uracil, and Thymine are pyrimidines.

mnemonic:"PUR As GoldCUT the PY"

Draw the basic structure of DNA