Chap 4: Metabolic Reactions

metabolism

sum of all chemical reactions

cellular metabolism

sum of all chemical reactions occurring in a cell’ metabolic reactions usually occur in pathways or cycles

anabolism

• provide material for maintenance, cellular growth/repair (ex. dehydration synthesis)

• small molecules built to larger ones and requires ATP made during catabolism

• H20 is produced

• create polysaccharides, triglycerides, and proteins

catabolism

• large molecules break down into smaller ones (ex. Hydrolysis)

• H20 is used

• Atp is produced, releases energy

enzyme

• proteins that control rates of catabolic and anabolic reactions

• greatly increase reaction rates

• not consumed, used repeatedly

• specific to a particular substrate (ability to recognize substrate depends on shape of active site)

metabolic pathways

• series of enzyme controlled reactions leading to formation of new product

• new substrate product of previous reaction

• each step catalyzed by different enzyme

rate-limiting enzyme

• regulatory enzyme that catalyzes on step of pathway typically sets rate for entire reaction sequence

• often first enzyme in the reaction

negative feedback

end product inhibits rate limiting enzyme, this is example of ___

cofactor

• typically inorganic and combine with enzyme to activate

• some help fold active site or bind enzyme to substrate

• can be ion, element, or coenzyme

coenzyme

• organic molecules that act as cofactor

• most are vitamins, essential to organic molecules that humans must get in diet to make enzymes work

Deficient/absent enzyme

• block metabolic pathway that it catalyzes

• results in accumulation of enzyme’s substrate. and a deficiency of its product

• Ex. Phenylketonuria (PKU- excess phenylalanine enters blood and poisons brain since enzyme not able to make phenylalanine into tyrosine)

energy

• ability to do work

• heat, light, sound, mechanical, chemical energy

• cannot be created or destroyed but can be changed

• held in chemical bonds and released when bonds are broken

cellular respiration

• process that transfers energy from molecules and makes it available for cellular use

• most metabolic reactions use chemical energy stored in ATP

oxidation

• releases energy from glucose and other molecules through loss of hydrogen atoms and their electrons

• enzymes lower activation energy needed for ____ in reactions of cellular respiration

ATP

• molecule that carries energy in a form the cell can use

• main energy carrying molecule

• consists of adenine, ribose, and 3 phosphate chains

• 2nd and 3rd phosphate attached by high energy bonds

ADP

• when ATP loses terminal phosphate

• can be converted back to ATP through phosphorylation

cellular respiration

• process that transfers energy from molecules and makes it available for cellular use

• glycolysis, citric acid cycle, electron transport chain

• final products are C02 H20 ATP HEAT

Anaerobic reactions

don’t require 02 and make little ATP

aerobic reactions

• require O2 and make most of ATP

• end products are C02 H20 and up to 36 ATP per molecule of glucose

glycolysis

• molecules are broken into 2 carbons

• breaks sugars and 2 ATP molecules formed

• anaerobic

citric acid cycle

• begins when acetyl CoA combines with oxalaocetic acid to produce citric acid

• 2 atp produced

electron transport chain

28 ATP produced

occurs in mitochondrion membrane

glycolysis

break down of glucose into 2 smaller molecules, anaerobic, occurs in cytosol

glycogenolysis

glycogen is broken down into glucose to provide immediate energy

glycogenesis

process of synthesizing glycogen from glucose

DNA

molecule that stores information on its sequence of nucleotides that instructs cell on how to synthesize proteins

proteins

_____ function as:

• enzymes

• blood proteins

• structural proteins

• antibodies

• cell membrane components

gene

sequence of DNA that contains enough information for making one protein

exome

small portion of the genome that codes for proteins

nucleotide

____ are composed of 5 carbon sugar (deoxyribose), phosphate group, nitrogenous base

DNA replication

process that produces an exact copy of a DNA molecule, occurs during interphase

• hydrogen bonds break between base pairs, strands unwind and separate

• new nucleotides pair with exposed bases, with DNA polymerase

• other enzymes connect new sugar-phosphate backbone

RNA differences from DNA

• single strand of nucleotides

• contains sugar, ribose

• uracil instead of thymine

• shorter

genetic code

• each unit of 3 RNA nucleotides and determines the amino acid sequence in a polypeptide

• gene directs synthesis of proteins

transcription

process of copying DNA sequence onto an RNA sequence

mRNA

type of RNA that carries genetic code from DNA to ribosome in cytoplasm

RNA polymerase

enzyme that catalyzes the formation of mRNA from the proper strand of DNA

codon

• 3-base sequence in mRNA

• 61 code for amino acids, 3 are stop codons

• Start Codon: AUG (methionine)

• Stop codons: UAG UGA UAA (have no tRNA anticodon)

Translation

• process of converting the genetic code, carried by MRNA into a sequence of amino acids that becomes a protein

tRNA

aligns amino acids during translation, along the mRNA strand on the ribosome and contains anticodon