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Bio > REVIEW 2 > Flashcards

REVIEW 2 Flashcards

1
Q

Structure of DNA

A

Nucleic Acid (4 different nucleotides)
Each is made of a phosphate group covalently bonded to a pentose sugar (deoxyribose) bonded to a nitrogenous base
Adenine, Thymine, Cytosine, Guanine

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2
Q

Direction of Bonded nucleotides

A

5’-3’

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3
Q

How are Nucleotides linked

A

Phosphodiester bonds

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4
Q

What forms the double strand?

A

Hydrogen bonds

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5
Q

Number of H-bonds between different bases and base pairs

A

2 h-bonds: Adenine to Thymine
3 h bonds: Guanine to cytosine
AND VICE VERSA

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6
Q

How are DNA strands made?

A

ANTIPARALLEL

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7
Q

Discovery of DNA structure

A

Rosalind Franklin
Photo 51 showed that DNA is a double helix with phosphate groups on the outside and nitrogenous bases on the inside

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8
Q

How is DNA packaged?

A

Nucleosomes
- Core = 8 histone proteins (positively charged) with DNA molecule (negatively charged) wrapped twice around
- DNA and histone proteins form chromatin (one extra histone protein)
This allows supercoiling into chromosomes

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9
Q

DNA sequences

A

2% is unique (these are genes and can be transcribed)
5-45% is highly repetitive
20% is structural sequences

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10
Q

Hershey-Chase Experiments

A

Determined that DNA, not proteins, was the genetic material
- Put radioactive phosphorus (DNA material) and sulfur (protein material) into a virus
- New viruses that were created had radioactive phosphorus, NOT sulfur in the pellet

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11
Q

DNA Replication Steps

A
  1. Helicase unzips parental DNA molecule (Breaking the Hydrogen Bonds between the double helix)
    Gyrase stabilizes the unizipped molecules
  2. Primase adds sequence of RNA bases (primer) to each parental DNA molecule at the replication origin
  3. DNA Polymerase III adds new nucleotides (deoxynucleoside triphosphates) to the RNA primer (at 3’ end only) to create a new complementary strand. This is continuous in the leading strand, but not in the lagging strand which is formed with Okazaki fragments later filled in by ligase (5’ to 3’ direction)
  4. DNA Polymerase I removes RNA primers and replaces them with DNA nucleotides
    OVERALL, process is semi-conservative; each daughter molecule is half old and half new.
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12
Q

Meselson and Stahl experiment

A

Showed that DNA replication is semi-conservative.

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13
Q

How is DNA used to make proteins

A

Central dogma: DNA -> transcription -> RNA -> translation -> protein

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14
Q

DNA vs RNA

A

DNA | RNA
Double strand | Single Strand
Deoxyribose | Ribose
Thymine | Uracil

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15
Q

DNA Transcription Steps

A
  1. Initiation - RNA polymerase unwinds (breaks H bonds) strands and bands to a promoter on the antisense DNA strand.
  2. Elongation - RNA polymerase adds RNA nucleotides (two phosphates lost to provide energy) to 3’ end of growing mRNA strand based on code
  3. Termination - RNA polymerase continues until the terminator sequence is released
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16
Q

What happens post-transcription

A

In eukaryotes, introns (non-coding regions) are removed to form mature mRNA (only exons remain to be translated into amino acids/proteins
Alternative RNA splicing by spliceosomes creates the possibility for MANY polypeptides from one gene.

17
Q

Ribosome structure

A

rRNA in nucleolus and proteins
Small/large subunit
Large subunit has A, P and E binding sites

18
Q

tRNA structure

A

T shpaed
Contains Anti-codons and amino acid binding site (the 3’ end @ sequence CCA)

19
Q

Translation steps

A
  1. Initiation - the small subunit of the ribosome binds to the mRNA at the start codon (AUG), tRNA (With correct anticodon) binds to mRNA, large subunit binds (1st tRNA in P site)
  2. Elongation (and translocation) - second tRNA comes into A site (complementary base pairing). Moves into P site, peptide bond formed, moves into E (exit) site
  3. Termination - STOP codon is reached, polypeptide chain released from tRNA in P site, ribosome disassembles
20
Q

What does differentiated mean in a cell?

A

Different genes turned on/expressed, meaning there are different proteins

21
Q

Epigenome

A

A collection of all the factors that modify/impact the activity/expression of genes without altering DNA sequences
1. Nucleosomes - more nucleosomes = more DNA packaged more tightly together, less transcription.
2. Methylation - methyl groups cause more tight coiling
3. Proteins - Transcription factors (act on RNA polymerase), activators and repressors
4. Environment - changes methylation, affects proteins

22
Q

Primary Protein Structure

A

Sequence and number of amino acids - linked by peptide bonds

23
Q

Secondary Protein Structure

A

Folding pattern: alpha helix or Beta pleated sheets (linked by Hydrogen Bonds)
Interaction between amino and carboxyl groups

24
Q

Tertiary Protein Structure

A

Folding pattern into 3D shape
Interactions between R groups (Disulfide bridges, Ionic bonds, Hydrogen Bonds, Van der Waals (hydrophobic) interactions

25
Q

Quaternary Protein Structure

A

NOT IN ALL PROTEINS
Links several polypeptide chains together (same binding as tertiary)
Linking prosthetic group to polypeptide

26
Q

KNOW HOW TO DRAW PEPTIDE BOND

A

Drawing here

27
Q

How is polarity of proteins determined?

A

R Groups

28
Q

Polar proteins functions

A

Form inner proteins and cytoplasm/extracellular portions of membrane proteins, active sites on enzymes

29
Q

Non polar proteins function

A

Outer portions of membrane proteins (toward phospholipid tails), embedded in cell membrane, active sites on enzymes.

30
Q

Protein functions

A

THMEDS
Transport (hemoglobin)
Hormonal communication (insulin, LH)
Movement (actin, myosin)
Enzymes/catalysts (catalase, amylase, lipase)
Defense (immunoglobulin, antibodies)
Structure (collagen, elastin, keratin)

31
Q

Fibrous vs globular proteins

A

Fibrous | Globular
Long, narrow | Rounded, spherical
Repetitive (no 3° structure) | Irregular
Structure/ support | Enzymes/ metabolism
Insoluble (in water)| Soluble (in water)
Actin, myosin, keratin, collagen | Hemoglobin, insulin, amylase

32
Q

Endergonic reactions

A

Anabolic
More energy IN (energy stored in products)
condensation (builds bonds)
Example: photosynthesis

33
Q

Exergonic reactions

A

Catabolic
More energy released
Offer involves hydrolysis
Example: cellular respiration

34
Q

Competitive inhibitors

A

Shape similar to substrate
Binds to active site
Increased substrate concentration reduces inhibition
Reversible inhibition

35
Q

Non-Competitive inhibitors

A

Shape NOT similar to substrate
Binds to other side (changes enzyme shape so regular substrate can’t bind)
Increased substrate concentration has no effect on inhibition
Usually irreversible inhibition

36
Q

How is lactase used in industry?

A

Lactase can pre-digest lactose in milk for lactose intolerant individuals

Bio (8 decks)

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