AP Review

1
AP Review

• Chapters 16-18

2
Fast Facts

• The role of DNA in heredity was first studied by
  using bacteria and viruses.
• Griffith (1928) was studying streptococcus
  pneumonia.
• Transformation a change in genotype and
  phenotype due to the assimilation of external DNA
  by a cell.
• Avery (1944) purified various chemicals from the
  heat killed bacteria to recreate Griffiths
  experiment. Only DNA worked.

3
Fast Facts

• Hershey and Chase performed experiments showing
  that DNA is the genetic material of T2 (a type of
  phage).

4
Fast Facts

• The monomer of nucleic acids are nucleotides
• - each consists of 3 parts a nitrogenous base,
  a pentose sugar called deoxyribose, and a
  phosphate group.
• - the base can be adenine (A), thymine (T),
  cytosine (C), or guanine (G).

5
Fast Facts
6
Fast Facts

• A series of enzymes carries out the steps of DNA
  replication
• DNA Polymerase enzyme that catalyzes the
  elongation of new DNA
• DNA strands line up in an antiparallel
  arrangement
• 5-------------3
• 3-------------5

7
Fast Facts

• DNA polymerase adds nucleotides only to the free
  3 end of a growing DNA strand.
• A new DNA strand can elongate only in the 5 ? 3
  direction.
• - leading strand DNA strand made by this
  mechanism works toward the replication fork

8
Fast Facts

• To elongate the other strand, polymerase must
  work in the direction away from the replication
  fork. This is the lagging strand
• - Okazaki fragment
• - DNA ligase joins Okazaki fragments to make a
  single DNA strand

9
Fast Facts

• Transcription and Translation are the two main
  processes linking genes to proteins
• - transcription is the synthesis of RNA under
  the direction of DNA
• - translation is the actual synthesis of a
  polypeptide, which occurs under the direction of
  mRNA

10
Fast Facts

• Nucleotide triplets specify amino acids
• - there are only 4 nucleotides to code for the
  20 amino acids
• - triplet code the genetic instructions for a
  polypeptide chain are written in the DNA as a
  series of three nucleotide words

11
Fast Facts

• - the codon AUG has a dual function it codes for
  the amino acid Methionine (Met) and it functions
  as a start signal, or initiation codon
• - RNA polymerase connects the RNA nucleotides as
  they base-pair along the DNA template

12
Fast Facts

• In translation, the cell interprets the genetic
  message and builds a protein accordingly
• - transfer RNA (tRNA) transfers amino acids
  from the cytoplasms amino acid pool to a
  ribosome
• - contains an anticodon that is complementary
  to the mRNA codon

13
Fast Facts
14
Sample Question

• Describe the steps of protein synthesis,
  beginning with the attachments of a messenger RNA
  molecule to the small subunit of a ribosome and
  ending with the release of the polypeptide from
  the ribosome. Include in your answer a discussion
  of how the different types of RNA function in
  this process.

15
Fast Facts

• A virus is a genome enclosed in a protective coat
• - a virus can be a DNA virus or an RNA virus
  depending on the kind of nucleic acid
• - the protein shell that encloses the viral
  genome is called the capsid
• Some viruses have viral envelopes, membranes that
  cloak their capsids
• - derived from the membrane of a host cell

16
Fast Facts
17
Fast Facts

• Phages replicate using either the lytic or
  lysogenic cycle
• Lytic cycle reproductive cycle that culminates
  in the death of the host.
• - during the last stage of the cycle the cell
  breaks open (or lyses) and releases the phages
  that were produced
• Lysogenic cycle replication of the phage genome
  without destroying the host

18
Fast Facts
19
Fast Facts

• Retrovirus
• - most complicated reproductive cycle of viruses
• - refers to the reverse directional flow of the
  genetic information
• - contain reverse transcriptase transcribes DNA
  from an RNA template
• - RNA ? DNA directional flow
• - DNA integrates as a provirus in the host cell

20
Fast Facts
21
Fast Facts

• The control of gene expression enables bacteria
  to adjust their metabolism to environmental
  change
• The lac operon regulates the synthesis of the
  enzymes needed to metabolize lactose.

22
Fast Facts

• -w/out lactose, no emzymes are made for
  metabolism
• - the regulatory gene, lacI is producing a
  repressor (prevents the transcription process)
  which blocks the RNA polymerase from working

23
Fast Facts
24
Fast Facts

• - when lactose is present, an inducer binds to
  the repressor making it inactive
• - RNA polymerase can then begin the
  transcription process and the gene can be
  expressed

25
Fast Facts
26
Sample Questions

• Describe the operon hypothesis and discuss how it
  explains the control of messenger RNA production
  and the regulation of protein synthesis in
  bacterial cells.