Plant Genetics - Genetic Material Flashcards

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1
Q

Characteristics of Genetic Material

A
  1. Contains all necessary info
  2. Replicates accurately
  3. Capable of change
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2
Q

Genetic Materials consist of….

A

DNA - in all living organisms and some viruses
RNA - only in certain viruses

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3
Q

Chemical Composition of DNA and RNA

A
  1. Macromolecule (large)
  2. Polymeric (many similar smaller molecules or monomers) monomers=nucleotide
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4
Q

What are the “building blocks” of DNA?

A

Nucleotides

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5
Q

What are the 3 parts of nucleotides?

A
  1. Pentose (5-carbon) Sugar
  2. Nitrogenous Base (nitrogen containing)
  3. Phosphate group (PO4)
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6
Q

What is the difference between a DNA and RNA Pentose sugar?

A

RNA-Ribose (OH)
DNA-Deoxyribose (H)

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7
Q

What Nitrogenous Bases are present in DNA?

A

Adenine
Guanine
Thymine
Cytosine

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8
Q

What Nitrogenous Bases are present in RNA?

A

Adenine
Guanine
Uracil
Cytosine

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9
Q

What are purines?

A

Nitrogenous Bases that are…
Nine-membered
Double-ringed
2 Types: Adenine and Guanine

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10
Q

What are Pyrimidines?

A

Nitrogenous Bases that are…
Six-membered
Single-ringed
3 Types: Cytosine, Thymine (DNA), Uracil (RNA)

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11
Q

What makes up a Nucleoside?

A

1.Sugar
2. Base
3. Purines

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12
Q

What makes up a Nucleotides?

A
  1. Sugar
  2. Base
  3. Phosphate group
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13
Q

What is a polynucleotide?

A

A chain of nucleotides
5’-3’ polarity

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14
Q

What are Chargaff’s Rules?

A
  1. A/T=1 or G/C=1
  2. (A+T)/(G+C) Varies
  3. (A+G)/(C+T)=1
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15
Q

What 3 pieces of Info is the Watson-Crick model

A
  1. DNA molecule is a polynucleotide chain
  2. Chargaff’s Rule: Amount of A = Amount of T
    and Amount of G = Amount of A
  3. Atomic structure is helical with 2 distinct regularities along the axis of 0.34 nm and 3.4 nm
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16
Q

What are the main features of Watson-Crick Model?

A
  1. 2 polynucleotide chains wound around each other in a right-handed double-helix
  2. 2 strands are oriented in opposite directions (antiparallel) 5’ to 3’(——>) and 3’ to 5’ (<——)
  3. Sugar-phosphate backbones on outside, bases oriented toward the central axis
  4. Bases of opposite strands are bonded together by (weak) hydrogen bonds
  5. Base pairs are 0.34 nm apart. A complete turn takes 3.4 nm with 10 base pairs per turn.
  6. Grooves of unequal size between the sugar-phosphate backbones (allows protein contact with bases)
17
Q

Genome

A

Chromosomes that contain all the DNA an organism possesses

18
Q

C value

A

Amount of DNA in haploid genome of a species

19
Q

Supercoiling

A

DNA Twisted in space about its own axis
Looped Domains
-organization
-allows for 10-fold increase in compaction
-Associated with proteins

20
Q

Eukaryotic Chromosome

A

a linear, double-stranded DNA molecule running throughout its length
complex with proteins

21
Q

Chromatin

A

complex of DNA and chromosomal proteins

22
Q

What are the two types of chromosomal proteins?

A
  1. Histone (most abundant, + charge, H1 H2A H2B H3 H4, highly conserved.
  2. Non-histone (many types, - charge, differ in # and type and control structural roles and folding and packing)
23
Q

What are the levels of chromatin packing?

A

Nucleosomes connected by linker DNA “ beads on string”
Nucleosomes associate with each other
Formation of loop domains of DNA
Condensation of chromatins
Chromosome shape is formed

24
Q

What happens in the first level of packing DNA?

A

Nucleosomes connected by linker DNA “ beads on string”
Winding of DNA around histones = nucleosome
DNA wrapped 1 3/4x around an octomer of histone proteins
2 copies of each H2A, H2B, H3, H4
Histone H1, binds to DNA where it joins and leaves the octomer
Condenses DNAQ by 7 fold

25
Q

What happens in the second level of packing?

A

Chomatin fiber of packed nucleosomes associate with each other

26
Q

What happens in the thrid level of packing and what is it’s significance?

A

Loop domains of DNA form, 10s-100k base pairs per loop, loops extend from the main chromosome axis
Importance: Condensation and Regulation of gene expression

27
Q

Where is the degree of packing highly condensed?

A

During mitosis

28
Q

Where is the degree of packing the most dispersed?

A

During the S phase

29
Q

What are the two types of chromatin condensation?

A
  1. Euchromatin (most common, normal condensation and de-condensation, highly transcribed regions)
  2. Heterochromatin (remains highly condensed, transcriptionally inactive regions such as centromeres, telomeres, and other specific sites)