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IB Bio > Review #2 presentation > Flashcards

Review #2 presentation Flashcards

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Biology 101 flashcards
1
Q

What is DNA

A

DNA is nucleic acid
made of nucleotides
4 of them in DNA
each with a different base

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2
Q

What is a nucleotide made of

A

phosphate group covalently bonded to a pentose sugar (deoxyribose) bonded to a nitrogenous base

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3
Q

what are the nitrogenous bases in DNA

A

Adenine, Thymine, Cytosine, and Guanine

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4
Q

Polynucleotide formation

A

binding nucleotides together in the 5’ to 3’ direction - condensation - removal of water and formation of covalent bonds called phosphodiester bonds
nucleotides can ONLY be added to the 3’

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5
Q

What are DNA nucleotides are linked together by?

A

Phosphodiester bonds in a 5’ to 3’ prime direction to form a single strand

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6
Q

How is a double-stranded DNA created

A

created when hydrogen bonds form between bases (A + T and C + G) between single strands

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7
Q

Purines (2 rings) always bind to what

A

Pyrimidines (1 rings): A + T and G + C

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8
Q

How do the antiparallel strands of DNA bind together to form a double helix

A

Hydrogen bonds form between bases

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9
Q

where do hydrogen bonds form between

A

2 between A + T and 3 between C + G

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10
Q

what technology was used to discover the structure of DNA

A

x-ray diffracion

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11
Q

How was the structure of DNA discovered

A
  • x-ray diffraction using crystallized DNA molecules
  • x-ray beams pass through crystallized DNA (for 10 hours) and diffract when they hit atoms (or other objects
  • scattering pattern is recorded on a special film
  • scattering pattern produces an image from which a 3D structure can be deduced
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12
Q

what is photo 51

A
  • photo by Rosalind Frankilin
  • shows that DNA is a double helix
  • Phosphate groups on outside of molecule
  • nitrogenous bases on inside of molecule
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13
Q

what happened to photo 51

A
  • it was stolen by Wilkins, Watson, and Crick
  • allowed them to build the first accurate model of the DNA structure
  • published their findings
  • all three got a Nobel Prize while Franklin died of cancer
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14
Q

nucleosome

A
  • core = 8 (+ charged) histone proteins with DNA molecule (- charged) wrapped twice around
  • DNA + histone proteins = chromatin
  • fundamental unit of DNA packaging - allows supercoilding of DNA into chromosomes
    - supercoiling prevents certain genes from being accessed by transcription factors
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15
Q

Hershey-Chase experiements in 1950

A
  • used bacteriophages with radioisotopes
  • Used radioactive phosphorus and radioactive sulfur
    - because phosphorus is in DNA and sulfur is in proteins
  • created one type of bacteriophage with radioactive phosphorus and another cell type with radioactive sulfur
  • Allowed two different types of phages to infect bacterial cells
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16
Q

Results of the Hershey-Chase Experiment

A
  • bacterial cells infected w radioactive phosphorus produced new phages with radioactive DNA
  • Bacterial cells infected w non-radiactive phosphorus produced new phages w non-radioactive DNA
  • None of the new viruses had radioactive sulfur (radioactive phosphorus was found in the pellet)
  • DNA was passed on to the new viruses, and protein was not
  • protein is not the genetic material and DNA is
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17
Q

Meselson and Stahl Experiments

A
  • used 2 different isotopes of nitrogen to grow bacteria (E. coli) cells (14N and 15N)
  • First, they grew bacterial cells in a medium containing 15N (heavier than 14N)
  • after many generations, all bacterial cells contained 15N in their DNA
  • 15N bacteria transferred to medium containing 14N
  • after 1 generation in 14N, bacteria removed and DNA isolated
  • Dissolved DNA in solution and centrifued
  • 14N DNA is light, so it would be found at the top and 15N at the bottom of the tub
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18
Q

results of the Meselson and Stahl Experiments

A
  • all DNA in first generation made of one strand with 14N and one strand with 15N, which were all found in the middle of the test tube
  • shows that DNA replication is semiconservative
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19
Q

Genes

A
  • unique, single copy sequences of DNA
  • made up of specific sequences of nucleotides that “code” for the sequence of amino acids that are put together (by ribosomes) to make up each protein
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20
Q

What does the DNA sequence determine

A
  • the amino acid sequence of every protein in a cell (its primary structure)
  • influences every level of protein structure after that
  • determines protein’s overall structure
  • affects its ability to function properly (ie sickle cell anemia)
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21
Q

why does DNA indirectly control the metabolism of every cell

A

because DNA sequences determine the amino acid sequence of every protein in a cell

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22
Q

some sequences of DNA code for proteins what are functions of other sequences of DNA that do not code for proteins

A

form barriers between protein coding regins
form telomeres
code for production of tRNA
(structural and highly repetetitive sequences)

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23
Q

what sequence type applies to DNA coding for proteins

A

unique

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24
Q

antisense vs sense strand

A

antisense is transcribed

sense is not

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25
Q

polymer

A

long strand molecule (RNA)

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26
Q

in prokaryotic cells

A

transcription and translation can happen at the same time

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27
Q

in all cells: polysomes

A

many ribosomes translating the same mrna into protein at the same time
indicates that the cell needs a lot of the same protein

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28
Q

Central Dogma of Molecular Biology

A
  • DNA -> transcription - RNA -> translation - protein
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29
Q

transcription

A

making mRNA (messenger RNA ) from DNA

30
Q

translation

A

make a protein (polypeptide chain) from mRNA

made by putting amino acids together

31
Q

Role of ribosomes in translation

A

“read” the mRNA code and use it to put amino acids together in the correct order based on the original DNA sequence to ultimately make a protein

32
Q

How are amino acids put together

A

by the genetic code (universal to all life)

- uses mRNA bases in sets of 3 (codons)

33
Q

what is RNA

A

nucleic acid (nucleotides)

34
Q

DNA vs RNA

A

D: double stranded
R: single stranded

D: deoxyribose (sugar)
R: ribose (sugar)

D: Guanine, Cytosine, Adenine, Thymine (bases)
R: Guanine, Cytosine, Adenine, URACIL (bases)

35
Q

Genetic Code and translation

A
  • mRNA molecules contain codons (series of triplet bases)
  • each codon specifies one amino acid (61 to 64)
  • start codon (AUG) specifies methionine
  • stop codon (3 of them; don’t code for amino acids, end translation)
  • code is universal to all life
    - allows gene transfer between species (ie: insulin gene into bacteria)
36
Q

proteins

A

made up of amino acids that are put together in a specific order based on the sequences of nucleotides in DNA
four levels of protein structure

37
Q

proteome

A

the entire collection of proteins in an individual (or in one of its cell types
each individual protein has a unique proteome and a genome because proteins are put together based on DNA

38
Q

what is the level of protein structure determined by

A

genetic information in DNA

39
Q

primary protein structure

A
  • sequence of amino acids

- amino acids linked by peptide bonds formed during translation

40
Q

secondary level of protein structure

A
  • folding pattern (basic) of polypeptide
  • two types: alpha helix (keratin in hair) and beta-pleated sheets (spider silk)
  • held by hydrogen bonds which stabilize structures of fibrous proteins
  • interactions between amino and carboxyl groups
41
Q

tertiary level of protein structure

A
  • folding pattern of polypeptide into 3D shape/globular proteins (for function/active site if an enzyme)
  • stabilized by disulfide bridges, ionic bonds, hydrogen bonds, hydrophobic interactions
  • Interactions between R groups
42
Q

quaternary level of protein structure

A
  • not in all proteins
  • linking several polypeptide chains together (uses same bonding as tertiary structure)
  • linking prosthetic group to polypeptide (ie haem in hemoglobin)
43
Q

amino acids -> dipeptides -> polypeptides

A

condensation - create peptide bonds between amino acids

44
Q

polypeptides -> dipeptides -> amino acids

A

hydrolysis - reactions break peptide bonds between amino acids

45
Q

dipeptide

A

two amino acids joined by a peptide bond

46
Q

polar (hydrophilic) and non-polar (hydrophobic) amino acids

A
  • determined by R groups
47
Q

polar (hydrophilic) amino acids

A
  • form inner portions and cytoplasm portions of membrane proteins (hydrophilic channels through cell membranes)
  • form active sites on enzymes (attract polar substrates)
  • allow proteins to dissolve in water
48
Q

non-polar amino acids

A
  • form out portions of membrane proteins (toward phospholipid tails) and proteins embedded in the cell membrane
  • form active sites on enzymes (attract non-polar substrates)
49
Q

what does protein shape/structure determine

A

it determines function

50
Q

protein functions with examples

A 
SHITS ME
Structure: collagen, spider silk
Hormones: insulin, glucagon 
Immunity: immunoglobins
Transport: haemoglobin
Sensation: rhodopsin 
Movement: actin, myosin
Enzymes: rubisco, catalase
51
Q

Fibrous vs Globular proteins

A

F: long, narrow
G: rounded, spherical

F: amino acids are repetitive (no 3 degree structure)
G: irregular

F: structure/support
G: enzymes/metabolism

F: insoluble (in water)
G: soluble (in water)

F: ex - actin, myosin, keratin, collagen
G: ex - hemoglobin, insulin, amylase

52
Q

what are enzymes

A
  • catalysts (globular proteins)
  • speed up reaction rates
  • lower activation energy (energy needed to start a reaction)
  • not used up in process
53
Q

How are enzymes specific to their substrates?

A
  • active site (place where substrate binds)
    - has specific shape for substrate like a lock and key
  • makes and breaks bonds in substrate while holding it in optimum position
  • binding of substrate to active site forms complex enzyme-substrate
53
Q

How are enzymes specific to their substrates?

A
  • active site (place where substrate binds)
    - has specific shape for substrate like a lock and key
  • makes and breaks bonds in substrate while holding it in optimum position
  • binding of substrate to active site forms complex enzyme-substrate
    - causes conformational (shape) change in active site (in R groups of amino acids) to make the substrate more reactive (induced fit)
54
Q

Temperature affect on enzyme activity

A
  • at optimum temp enzyme works best
  • more collisions between molecules as temperature increases
  • below optimum the rates slow down
  • above optimum causes enzymes to denature
    - (lose characteristic shape- permanent if peptide bonds break)
55
Q

pH affect on enzyme activity

A
  • at optimum pH the enzyme works best

- below or above the enzymes denature (ions interact with hydrogen bonds)

56
Q

substrate concentration effect on enzyme activity

A
  • activity increases as substrate concentration increases up to a point where activity plateaus
  • when enzymes are saturated they are working as fast as they can and all active sites areoccupied
57
Q

Metabolism

A

the sum of all the chemical reactions that occur in a living organism

58
Q

What are the different metabolic pathways

A

anabolic

catabolic

59
Q

Anabolic pathway

A
  • building of complex molecules
  • Endergonic - more energy IN to build bonds, often involves condensation)
    ie photosynthesis
60
Q

Catabolic pathway

A
  • breaking down of complex molecules
  • exergonic: more energy released as chemical bonds are broken, often involves hydrolysis, digestive
    ie cellular respiration
61
Q

What are almost all metabolic reactions catalyzed by?

A

enzymes

without them, biological reactions would not occur fast enough for us to survive

62
Q

What are the two inhibitors enzymes are affected by

A

Competitive and non-competitive (allosteric)

63
Q

Differences between competitive and non-competitive inhibitors

A

C: shape is similar to substrate
NC: shape is NOT similar to substrate

C: Binds to active site - blocks active site and prevents substrate from binding
NC: binds to other site (allosteric site) - causes change in active site shape so substrate cannot bind

C: increase in substrate concentration reduces inhibition
NC: increase in substrate concentration does NOT reduce inhibition

C: reversible inhibition
NC: irreversible inhibition (usually)

64
Q

What are metabolic pathways regulated by

A

end-product inhibition

65
Q

Define metabolic pathway

A

specific steps in a metabolic reaction

66
Q

What does every metabolic pathway begin and end with

A

begins with specific molecule
ends with a specific product

  • many steps in metabolic pathway
    - each catalyzed by own specific enzyme bc the substrate changes shape after each reaction
67
Q

What can the final product of a metabolic pathway act as

A

allosteric inhibitor

68
Q

What happens when the end product is present in sufficient amounts in a metabolic reaction

A
  • end-product inhibition shuts the “assembly line” down to prevent the cell from wasting resources
  • able to bind to an allosteric site on the first enzyme in the metabolic pathway
    - causes active site to change shape, making it non-functional and shutting down the entire pathway
69
Q

what is a negative feedback mechanism

A

the outcome of the mechanism causes the opposite effect

in terms of the metabolic pathway: more product = less activity of they pathway

70
Q

what can allosteric regulation do to an enzyme’s activity

A

inhibit or stimulate activity

71
Q

Lactase

A
  • Lactase (lactose glucose + galactose) is made for lactose-intolerant people (gas is produced in their stomachs because they lack the enzyme to break down lactose)
  • obtained from yeast/bacteria
  • pre-digest lactose in milk/dairy products using immobilized enzyme (trapped in calcium alginate beads)
  • makes products sweeter (without adding sugar)

IB Bio (26 decks)

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