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biochemistry
study of organic molecules
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CHNOPS
- all have CH
- most have NO
- some have PS
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5 types of organic molecules
- carbohydrates
- lipids
- proteins
- nucleic acids
- ATP
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catabolism
- aka hydrolysis
- complex macromolecules break down into simple components
- water added
- ABCD + H2O -> A+B+C+D
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anabolism
- aka dehydration synthesis
- simple molecules recombine to form complex macromolecules
- water removed
- A+B+C+D -> ABCD + H2O
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carbohydrates
- simple sugars, starches, glycogen, cellulose
- all contain CHO (1:2:1 ratio)
- most end in -ose
- easily metabolized by the body
- provide most energy used by the body
- 3 classes: monosaccharides, disaccharides, polysaccharides
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monosaccharides
- simplest sugars
- 3-7 carbons
- triose, tetrose, pentose, hexose, heptose
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*pentose*
- C5-H10-O5
- forms isomers deoxyribose and ribose
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*hexose*
- C6-H12-O6
- forms isomers glucose, fructose, galactose
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disaccharides
- 2 monosaccharides joined anabolically
- maltose, sucrose, lactose
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maltose
glucose + glucose
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sucrose
glucose + fructose
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lactose
glucose + galactose
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polysaccharides
10-100 monosaccharides joined anabolically
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*glycogen*
- many glucose molecules recombined anabolically
- only stored in liver and skeletal muscle cells until needed
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cellulose
- plant starch aka fiber
- no nutritional value
- required for proper digestion
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lipids
- 18-25% of body weight in lean adult
- contain CHO (no 1:2:1 ration - less O2)
- mostly hydrophobic (do not dissolve in water)
- dissolve in alcohol, ether, chloroform, xylene, mineral spirits, other lipids
- contain 2x energy of carbs or protein
- energy is not efficient b/c fats are difficult to breakdwon
- unlimited ability to store fats (lots of adipocytes)
- excess carbs/proteins converted to fat and stored
- 4 classes: triglycerides, phospholipids, steroids, eicosanoids
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triglycerides
- most abundant lipid
- solid (wax) or liquid (oil) at room temp
- always form fatty acid + glycerol when broken down
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phospholipids
- lipid found in cell membranes
- ampiphathic - polar (react w/water) head/non-polar (react w/ other lipids) tail
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steroids
- lipid with unique 4 carbon ring structure
- 4 types: testosterone/estrogen, vitamin D, cholesterol, bile salts
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testosterone/estrogen
- steroid
- sex hormone
- secondary sex characteristics
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vitamin D
- steroid
- made in skin
- for bone development
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cholesterol
- steroid in cell membranes
- necessary for vitamin D
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bile salts
- steroid
- breaks down fats during digestion
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eicosanoids
- 20 carbon fatty acid (arachiadonic acid)
- 2 types: prostaglandins, leukotrinnes
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prostaglandin
- eicosanoid
- regulate temp
- keep air passages open
- clot blood
- prevent ulcers
- determine response to hormones
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leukotrinne
- eicosanoid
- helps control allergic and inflammatory responses
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*proteins*
- contain CHNO sometimes S
- complex, wide variety of functions
- **chain of amino acids joined by peptide bonds**
- various shape depending on protein
- 4 structures: primary, secondary, tertiary, quaternary
- 5 functions: contractile, structural, catalytic, immunological, transport
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primary protein structure
long, linear, one-dimensional protein
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secondary protein structure
primary protein folds into pleated sheets or coils into a helix
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tertiary protein structure
- protein folds back on itself
- AAs originally on opposite ends are next to each other
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quaternary protein structure
2 or more protein chains twist together
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contractile protein
proteins that shorten (ex. actin/myosin)
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structural protein
proteins that form structures (ex. collagen)
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catalytic proteins
enzymes that speed up reactions n the body
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immunological proteins
antibodies
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transport proteins
ex. hemoglobin
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*denature*
when an S, Q, or T protein stops functioning after it encounters a hostile environment (ex. excessive heat or acid)
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enzymes
- unique proteins that speed up chemical reactions
- most end in -ase
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holoenzyme
a complete enzyme
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apoenzyme
protein portion of an enxyme
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co-enzyme
organic non-protien portion of an enzyme
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co-factor
metallic non-protein portion of an enzyme
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*substrates*
- specific molecules in the body that enzymes are programmed to seek out
- each enzyme has a unique substrate
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active site
- reigon on enzyme where it combines with substrate
- induced fit: combines like lock and key
- reactions occur and products are produced
- products move away from site of reaction
- enzyme and substrade split
- enzyme is free to cause another reaction
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nucleic acids
- largest molecules in the body
- CHNOP
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nucleotide
- basic structure of nucleic acid
- pentose sugar (C5): deoxyribose or ribose
- phosphate group: forms backbone of NA
- nitrogenous bases: Adenine, Guanine, Cytosine, Thymine, Uracil
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DNA
- always in the nucleus (never leaves)
- contains heredity info for entire organism, instructions for making every protein in the body
- double stranded - twisted into double helix
- pentose sugar is deoxyribose
- bases are A G C T
- A = T
- G = C
- paired bases joined by hydrogen bonds
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RNA
- found in nucleus and cytoplasm
- carries out DNA instructions for making protien
- single stranded - linear or folded
- pentose sugar is ribose
- bases are A G C U
- A = U
- G = C
- paired bases joined by hydrogen bonds
- 3 types: mRNA, rRNA, tRNA
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mRNA
- messenger RNA
- copy of DNA that takes genetic code to ribosome
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rRNA
- ribosomal RNA
- small part of ribosome that reads mRNA
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tRNA
- transfer RNA
- attaches to amino acids in cytoplasm
- brings AAs into ribosome to make protein when signaled
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protein synthesis
- how proteins are made
- 2 steps: transcription and translation
- DNA contains blueprint
- 20 different amino acids
- most proteins contain 100 - 1000 AAs
- **number, type, and order of AAs determine specific protein**
- each AA is coded by 3 nitrogen bases
- unique codons on mRNA determine when protein synthesis starts/stop
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triplets
3 nitrogen bases on DNA
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codons
3 nitrogen bases on mRNA
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anticodons
3 nitrogen bases on tRNA
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initiator/start codon
- AUG
- when ribosome reads it, protein synthesis begins
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stop codon
- UAA, UAG, UGA
- when any one is read, protein synthesis stops
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transcription
- 1st step in protein synthesis
- occurs in the nucleus
- geneitic code in DNA is copied to mRNA
- initiated by RNA polymerase - enzyme that initiates transcription
- --attaches to DNA
- --causes it to uncoil
- --breaks hydrogen bonds between DNAs nitrogen bases
- --separates into 2 strands - sense strand and antisense strand
- as it reads, it copies entire sense strand to a strand of mRNA
- SNURPS remove introns and splice exons together
- mRNA (exons) leaves nucleus and travel to ribosome
- sense/antisense strands re-coil into helix
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sense strand
strand of DNA that RNA polymerase reads
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antisense strand
strand of DNA that RNA polymerase does not read
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exon
info on the sense strand that is used to code for protein
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intron
info on the sense strand that is NOT used to code for protein
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translation
- 2nd step in protein synthesis
- occurs in cytoplasm at ribosome
- genetic code in mRNA is transferred to a protein
- 3 steps: initiation, elongation, termination
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initiation
- mRNA reaches ribosome
- attaches to rRNA
- rRNA reads codons
- when AUG is read, large and small ribosomal subunits lock together over mRNA
- 1st tRNA and its AA enter P-site
- codon and anticodon bind - initiation complete
- 1st AA is always methionine
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elongation
- lengthening of AA chain
- code in mRNA is translated to a protein
- 2nd tRNA/AA enter A site (amino acid site)
- peptide bond forms between AA1 and AA2
- codon and anticodon bind, filling ribosome
- ribosome slides to next codon
- 1st tRNA/AA now in cytoplasm
- hydrogen bond between 1st tRNA/AA breaks
- 2nd tRNA/AA slide from A site to P site
- A site empty
- process repeats
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termination
- when rRNA reads stop codon
- UAA, UAG, UGA (any one)
- release factor enzyme activated - splits ribosome back into 2 subunits and cuts protein away
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ATP
- preferred source of energy required by the body
- obtained from sugar, AAs, fatty acids, glycerol
- produced in the mitochondria
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