Lecture 3 - Introduction to Nucleic Acids Flashcards Preview

Unit 1 - Molecular and Cellular Principles of Medicine > Lecture 3 - Introduction to Nucleic Acids > Flashcards

Flashcards in Lecture 3 - Introduction to Nucleic Acids Deck (27)
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1
Q

What is the central dogma of molecular biology

A

DNA Replication > Transcription (to RNA) > Translation (to protein)

2
Q

What is the general structure of a nucleic acid in DNA?

A

Sugar with base attached at 1’ and phosphate on 5’, no 2’ OH

3
Q

What is the difference between DNA and RNA?

A

RNA has 2’ OH

4
Q

What is the difference between a nucleotide and nucleoside?

A

Nucleotide has a 5’ phosphate, nucleoside has 5’ OH

5
Q

What is the direction of phosphodiester bonds?

A

5’ to 3’

6
Q

What charge does this create for the backbone of the DNA molecule?

A

Negatively charged

7
Q

What is the general structure of a pyrimidine?

A

6 member ring with N at 1st and 3rd carbons

8
Q

What bases are pyrimidines?

A

Cytosine, thymine, and uracil

9
Q

What is the different between thymine and uracil?

A

Thymine demethylated at the 5th carbon = Uracil

10
Q

What is the general structure of a purine?

A

6 member ring attached to 5 member ring

11
Q

What bases are purines?

A

Adenine and guanine

12
Q

What are some functions for nucleotides?

A

Building blocks for nucleic acid polymers (DNA, RNA), energy carriers (ATP, GTP), coenzymes (FAD, NADP), precursors for secondary messangers (cAMP)

13
Q

How are strands of DNA arranged?

A

In antiparallel strands with complementary base pairing

14
Q

Which bases pair with which and with how many hydrogen bonds?

A

G-C (3 H bonds), A-T (A-U) (2 H bonds)

15
Q

What are the structural features of B DNA?

A

Right handed helix, 90 degrees from bp to backbone, 1 turn of helix = 10.5 bp, 34 angstroms, major and minor grooves

16
Q

What are the two other forms or DNA?

A

A DNA and Z DNA

17
Q

Important facts about A DNA?

A

Right handed, 11 bp/turn, essentially shorter, squater version of B DNA

18
Q

Important facts about Z DNA?

A

Left handed, 12 bp/turn, elongated

19
Q

DNA bending facilitates what…

A

Protein DNA interactions!

20
Q

What are some factors in DNA’s denaturation?

A

Size, GC content, [salt], pH

21
Q

How is DNA packaged into cells?

A

Wound around nucleosome (comprised of 8 histone proteins), fold into 30 nm fiber, form loops, and ultimately coil into chromosome.

22
Q

What is the difference between euchromatin and heterochromatin?

A

Euchromatin is loosely packed (being transcribed) and heterchromatin is tightly packed.

23
Q

What causes negative supercoiling? What about positive?

A

Underwound DNA = negative

Overwound DNA = positive

24
Q

What enzymes exist to relieve supercoiling?

A

Topoisomerases

25
Q

What is the difference between type 1 and type 2 topoisomerase?

A

Type 1: cuts one strand to relieve supercoiling

Type 2: cuts both strands

26
Q

In what ways is RNA different than DNA?

A
  1. Single stranded 2. Shorter in length 3. Complex tertiary structure 4. Unstable
27
Q

What are the types of RNA?

A

mRNA - contains info from DNA and is template for protein synth

NON-Coding RNAs; rRNA, tRNA, miRNA, ribozymes