Molecular Biology Lecture

Molecular Biology

Fig. 10-1a

Head DNA Tail Tail fiber

Fig. 10-1b

Phage

Radioactive protein

Bacterium

Empty protein shell

Radioactivity in liquid

Phage DNA DNA

Batch 1 Radioactive protein

Centrifuge Pellet

1 Mix radioactively

labeled phages with bacteria. The phages infect the bacterial cells.

Batch 2 Radioactive DNA

2 Agitate in a blender to

separate phages outside the bacteria from the cells and their contents.

3 Centrifuge the mixture

so bacteria form a pellet at the bottom of the test tube.

4 Measure the

radioactivity in the pellet and the liquid.

Radioactive DNA Centrifuge Pellet

Radioactivity in pellet

DNA Structure

Fig. 10-3b

Fig. 10-3a

Fig. 10-2aa

Nitrogenous base (A, G, C, or T) Phosphate group

Thymine (T)

Sugar (deoxyribose)

Fig. 10-2b

Thymine (T)

Cytosine (C)

Pyrimidines

Adenine (A)

Guanine (G) Purines

Fig. 10-2c

Nitrogenous base (A, G, C, or U) Phosphate group

Uracil (U)

Sugar (ribose)

Fig. 10-3da

Base pair

Ribbon model

Fig. 10-4a-3

Nucleotides Parental molecul e

Both parental strands serve as templates

Two identical daughter molecules of DNA

DNA replication occurs during S phase of the Cell Cycle

Fig. 10-4b

Fig. 10-5b

5 end P 4 3

P

5 2

1

3 end 2 3 1 4 5

P

P

P

P

P

P 3 end

5 end

Fig. 10-5a

Origin of replication

Parental strand Daughter strand

Bubble

Two daughter DNA molecules

Fig. 10-5c

DNA polymerase molecule

5 3

3 5

Parental DNA

3 5

5 3

DNA ligase Overall direction of

Daughter strand synthesized continuously Daughter strand synthesized in pieces

Protein Synthesis occurs during G0, G1 and G2 of

Fig. 10-6a-3

DNA

Transcription

RNA Nucleus Cytoplasm Translation

Protein

Fig. 10-7a

DNA strand

Transcription

RNA Codon Translation

Polypeptide Amino acid

Fig. 10-9b

RNA polymerase DNA of gene Promoter DNA

Terminator DNA

1

Initiation

2

Elongation

3

Termination

Completed RNA

Area shown in Figure 10.9A

Growing RNA

RNA polymerase

Third base

First base

Fig. 10-8a

Second

Fig. 10-12a

tRNA molecules

Growing polypeptide

Large subunit

mRNA

Small subunit

Fig. 10-12c

Next amino acid to be added to polypeptide

Growing polypeptide

tRNA mRNA

Codons

Fig. 10-14-4

Amino acid

Polypeptide A site

P site

Anticodon mRNA

Codons 1 Codon recognition

mRNA movement

Stop codon 2 Peptide bond formation New peptide bond

3 Translocation

Mutations

Fig. 10-16a

Normal hemoglobin DNA

Mutant hemoglobin DNA

mRNA

mRNA

Normal hemoglobin

Sickle-cell hemoglobin

Glu

Val

Plasmodium falciparum

Fig. 10-16b

Normal gene

mRNA Protein

Met

Lys

Phe

Gly

Ala

Lys

Phe

Ser

Ala

Base substitution

Met

Base deletion

Missing

Met

Lys

Leu

Ala

His