Central Dogma

Question 1

Central Dogma

Explains the

Answer 1

Explains the flow of genetic material within biological systems

Question 2

DNA Double Helix

Complementary base pairing in the DNA double helix

Answer 2

Complementary base pairing in the

DNA double helix

Question 3

Chemical Properties of DNA

____ ____ determines specificity of base pairing
•In addition, stability is determined by the ____ ____ between ___ ___

Answer 3

• Hydrogen bonding determines specificity of base pairing
• In addition, stability is determined by the hydrophobic between stacked bases.

Question 4

Chromosome Structure of Prokaryotes

_____ is the coiling of the ___ ____ upon itself
•Chromosome of bacteria is a___ ____ DNA molecule
•Resides in a region of the cell known as the ____
•Chromosome is arranged into ___ and as a whole is ____ supercoiled

Answer 4

• Supercoiling is the coiling of the DNA axis upon itself
• Chromosome of bacteria is a closed circular DNA molecule
• Resides in a region of the cell known as the nucleoid
• Chromosome is arranged into loops and as a whole is negatively

supercoiled

Question 5

Chromosome Structure of Eukaryotes

•Packing of eukaryotic DNA is required for ___________
•Chromosomes have ____
____: ___ ___proteins which bind tightly to ___ (____ ____)
•5 types of histones: ___ __ ___ ___ ___
_____=___ + ____
•

Answer 5

•Packing of eukaryotic DNA is required for all of it to fit in the nucleus
•Chromosomes have structure
•Histones: small basic proteins which bind tightly to DNA (phosphate backbone)
•5 types of histones: H1, H2A, H2B, H3, H4
•Chromatin=DNA + nucleoproteins
•

Question 6

Nucleosomes

•Appearance as _______
•Core particle (purple)
•_______bp of DNA wound around a ___ ___ (2 each of ___ ___ ___ ___). Forms ___ handed supercoil.
•Compacting of nucleosomes together with ____ ____ and ___ histones.
•
•Note: during replication histones segregate ____. “Old” histones stay with template (parental) strand; “New” histones go on new strand

Answer 6

•Appearance as beads on a string.
•Core particle (purple)
•140-200 bp of DNA wound around a histone octamer (2 each of H2A, H2B, H3, H4). Forms a left handed supercoil.
•Compacting of nucleosomes together with linker DNA and H1 histones.
•
•Note: during replication histones segregate conservatively. “Old” histones stay with template (parental) strand; “New” histones go on new strand

Question 7

DNA Organization in Chromosome Structure

• Nucleosome structures condense into a ____ filament.
• Chromatin is further condenses and folds in a__ ___ pattern into a filament which is _____ in diameter. This filament is a ____ consisting of ___ ____ per ____
• The H1 histones stabilize the ____ structure.
• The 300 nm filaments form ____ which are attached to a ____ ___ giving rise to condensed ____ chromosomes.

Answer 7

• Nucleosome structures condense into a 30nm filament.
• Chromatin is further condenses and folds in a zig zag pattern into a filament which is 300nm in diameter. This filament is a solenoid consisting of 6 nucleosomes per turn.
• The H1 histones stabilize the solenoid structure.
• The 300 nm filaments form loops which are attached to a protein scaffold giving rise to condensed metaphase chromosomes.

Question 8

Human Chromosomes

• With the exception of ___ cells and ___ ____ cells, human cells contain ___ copies of chromosomes.
• Total number of chromosome for a cell is __, 22 pairs of autosomes and a pair of sex chromosomes.

Answer 8

• With the exception of germ cells and red blood cells, human cells contain two copies of chromosomes.
• Total number of chromosome for a cell is 46, 22 pairs of autosomes and a pair of sex chromosomes.

Question 9

Summary

Answer 9

•The central dogma describes the flow of genetic material through a biological system.
•DNA is organized into chromosomes by associating with histone proteins.
•The organization of DNA into chromosomes occurs at different levels.
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