Nucleic Acids and Proteinswww.psmag.com

Structure & Function PART 2

EUKARYOTIC CHROMOSOMES

a structure made of DNA and associated proteins carries part or all of a cell’s genetic information

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BACTERIAL CHROMOSOMES

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CHROMOSOME NUMBER

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Sum of ALL chromosomes in a cell

NUCLEIC ACIDS: DNA & RNA

linear array of NUCLEOTIDES

PURINES & PYRIMIDINES

PHOSPHODIESTER LINKAGES BETWEEN

NUCLEOTIDES

DNA (Deoxyribonucleic acid)

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DNA was discovered in 1869 by Fredrich Miescher by isolating the nuclei of white blood cells, he extracted an acidic molecule he called nuclein

FUNCTIONSDNA carries genetic info from one generation to the next DNA becomes read and transcribed so that proteins are made and traits are expressed DNA must be replicated each time cells divide

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THE DNA STRUCTURE

ROSALIND FRANKLIN MAURICE WILKINS JAMES WATSON & FRANCIS CRICK

PROPERTIES IN A DOUBLE HELIX

The strands of DNA are antiparallel

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PROPERTIES IN A DOUBLE HELIX

The strands are complimentary (CHARGAFF’S RULE)www.ric.edu

PROPERTIES IN A DOUBLE HELIX

There are Hydrogen bond forces

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PROPERTIES IN A DOUBLE HELIX

There are base stacking interactions

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PROPERTIES IN A DOUBLE HELIX

There are 10 base pairs per turn

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RNA (Ribonucleic acid)

In the early 1900s, Phoebus Levene isolated two types of nucleic acid: RNA and DNA. In 1919, he proposed that both were made up of individual units called nucleotides.

Each nucleotide was composed of one of four nitrogen-containing bases, a sugar, and a phosphate group

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FUNCTION & TYPERNA helps to assemble amino acids into proteins (Remember: proteins that determine traits)

3 Types: mRNA, rRNA, tRNA

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PROPERTIES OF RNASINGLE-STRANDED

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PROPERTIES OF RNARIBOSE SUGAR

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PROPERTIES OF RNACOMPLEMENTARY BASES

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PROTEINS

Proteins control the phenotypes (traits) of organisms

Proteins regulate our cell functions (chemical reactions)

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STRUCTURE

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Example: HIV protein shell structure

QUESTION #1:

D

Identify this molecule:

A. amino acid

B. carbohydrate

C. RNA

D. DNA

QUESTION #2:

D

Identify the following molecule

A. amino acid

B. hydrogen bond

C. protein

D. Nucleotide

C

CH2

O

Phosphate Group

Deoxyribose

Nitrogenous Base

QUESTION #3:

C

How many types of RNA are there?

A. 1

B. 2

C. 3

D. 4

QUESTION #4:

A

Which of the following have hydrogen bonds between nitrogenous bases?

A. DNA

B. RNA

C. BOTH

QUESTION #5:

“Transfer” amino acids to ribosomes/ delivery system of amino acids to

ribosomes during protein synthesis

What is the function of tRNA?

QUESTION #6:

B

Which of the following is found in BOTH DNA and RNA?

A. phosphate group, guanine, uracil

B. phosphate group, guanine, cytosine

C. ribose, phosphate group, uracil

D. deoxyribose, phosphate group, thymine

QUESTION #7:

“Messenger” serves as template during protein synthesis/ RNA version of the

gene encoded by DNA

What is the function of mRNA?

QUESTION #8:

B

Which of the following describes the structure of DNA?

A. double-stranded RNA molecule

B. double-stranded helix molecule

C. double-stranded RNA helix

D. single-stranded RNA helix

QUESTION #9:

“Ribosomal” binds with proteins to form the ribosome during protein

synthesis

What is the function of rRNA?

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QUESTION #10:

amino acid sequence

Describe the primary structure of proteins

THE SEARCH FOR THE GENETIC MATERIAL

Before DNA was established as the genetic material in cells, scientists knew:

there was a connection between chromosomes and inherited traits the genetic material had to control the production of enzymes and proteins the genetic material had to be able to replicate itself with accuracy and still allow mutations to occur

THE CANDIDATES: PROTEIN AND DNA

Once T.H. Morgan’s group showed that genes are located on chromosomes, the two constituents of chromosomes - proteins and DNA - were the candidates for the genetic material Until the 1940s, the great heterogeneity and specificity of function of proteins seemed to indicate that proteins were the genetic material However, this was not consistent with experiments with microorganisms, like bacteria and viruses

GRIFFITH’S TRANSFORMATION EXPERIMENT (1928)

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Oswald Avery, Maclyn McCarty and Colin MacLeod EXPERIMENT

(1943)

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Oswald Avery, Maclyn McCarty and Colin MacLeod EXPERIMENT (1943)

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Oswald Avery, Maclyn McCarty and Colin MacLeod EXPERIMENT (1943)

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ALFRED HERSHEY & MARTHA CHASE (1952)

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• Concluded that the injected DNA of the phage provides the genetic information that makes the infected cells produce new viral DNA and proteins, which assemble into new viruses

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TRANSDUCTION EXPERIMENT

IS IT PROTEIN?

SO, IS IT DNA?

QUESTION #11: (BY PAIR)

5’ GCC AAT 3’

WHAT IS THE COMPLEMENTARY STRAND OF THE GIVEN DNA TEMPLATE:

5’ ATT GGC 3’

QUESTION #12:

A

Which of the following is a DNA template?

A. GGC TTA GGT

B. TTA GGU GGA

C. AAU CCT AAG

QUESTION #13: (BY PAIR)

showed that genes are located on chromosomes, the two constituents of chromosomes - proteins and DNA - were the candidates for the genetic material

What is the contribution of TH Morgan’s group to molecular genetics?

QUESTION #14:

What are the two strains of Streptococcus used in the transformation experiments by Griffith?

the “rough” avirulent strain and the “smooth” virulent strain

QUESTION #15: (BY PAIR)

According to Griffith’s Experiment, why did he suggest that DNA is the genetic material?

DNA as transforming principle: “transformed” avirulent strains to

virulent strains

QUESTION #16: (BY PAIR)

How did Hershey and Chase monitor the fate of DNA if their experiment

radioactive labelling with P

QUESTION #17: (BY PAIR)

How did Hershey and Chase monitor the fate of PROTEINS if their experiment

radioactive labelling with S