Chapter 4 PPT Flashcards
What is metabolism?
The sum of all chemical reactions in the body
What is cellular metabolism?
sum of all chemical reactions occurring in a cell. Metabolic reactions usually occur in pathways or cycles
What are the two metabolic reactions?
Anabolism and Catabolism
What is Anabolism?
Small molecules are built into larger ones, requires energy
What is Catabolism?
Larger molecules are broken down into smaller, releases energy
Anabolism provides
materials for maintenance, cellular growth, and repair. Requires ATP made during catabolism
Example of Anabolsim?
Dehydration Synthesis
In Dehydration Synthesis, smaller
molecules are bound together to form larger ones
What is produced in hydration synthesis?
H2O
Anabolism used to produce
polysaccharides, proteins, and triglycerides
Catabolism breaks
down larger molecules into smaller ones; ATP is produced
Example of Catabolsim?
Hydrolysis
Catabolism used to
decompose carbohydrates, proteins, lipids
Catabolism uses
H2O to split the substances
Catabolism is reverse of
dehydration synthesis
All cells perform
catabolic and anabolic reactiosn
Enzymes control
rates of both catabolic and anabolic reactions
enzymes are globular proteins that
catalyze specific reactions
enzymes increases
rates of chemical reactions
enzymes lower
the activation energy necessary to start reactions
Shape of enzyme is
vital to its functioning
Factors that can alter conformation of an enzyme
Excess Heat Radiation Electricity Specific Chemicals Extreme pH Values Some Poisons
What is Denaturation?
Inactivation of enzyme due to an irreversible chang in its conformation
What is a “Metabolome”
All small molecules that are part of the metabolism in a cell, tissue, organ, organism
Human Metabolome Database stores
vast amounts of information about these molecules, also called :metabolites”
What are metabolic pathways?
Sries of enzyme-controlled reactions leading to formation of a product. Each new substrate is the production of the previous reaction
Names of enzymes often
Contain name of substrate, and ends in ase
Each step of a pathway is
catalyzed by a different enzyme
A regulatory enzyme that catalyzes one step of pathway typically
sets rate for entire reaction sequence
What is the rate-limiting enzyme ?
Number of molecules of this enzyme is limited. and is often the first enzyme in the reaction sequencec
What is a cofactor?
Non-protein substance that combines with the enzyme to activate it
Cofactor- some help fold
active site into proper conformation
Cofactor - some help bind
enzyme to substrate
Cofactor- can be
ion, element, or small organic molecule
Coenzyme is
organic molecule that acts as a cofactor.
Coenzyme - most are
vitamins, which are essential organic molecules that humans must get from their diet
Inborn Errors of Metabolism
Deficient or absent enzyme blocks metabolic pathway that it catalyzes. Results in accumulation of enzymes substrate, and a deficiency of its product
Example of Inborn Errors of Metabolism
Phenylketonuria (PKU)
What is PKU?
Missing/nonfunctional enzyme blocks conversion of amino acid, phenylamine, into the amino acid, tyrosine. Excess phenylalnine enters blood and poisions the brain. Can be treated with special diet
Energy is
the capacity to change something, or the ability to do work
Common forms of energy
heat, light, sound, electrical energy, mechanical energy, chemical energy
Cellular respiration is a
process that transfers energy from molecules, and makes it available for cellular use
ATP carries
energy in a form the cell can use. Main energy carrying molecule in the cell.
ATP consists of what 3 portions?
Adenine
Ribose (A Sugar)
3 Phosphates In A Chain
SEcond and third phosphates are
attached by high energy bonds; energy can be quickly transferred to other molecules
Wen ATP loses terminal phosphate, it
becomes ADP
ADP can be converted back into ATP by
attaching a third phosphate, called phosphorylation
Phosphorlation requires
energy from cellular respiration
ATP and ADP cycle
back and forth between cellular respiration and energy-utilizing reactions
Energy is held in
chemical bonds, and released when bonds are broken
Oxidation releases energy from
glucose
In cells, enzymes initiate oxidation by
lowering activation energy
Energy is transferred to ATP, whats the ratio?
40% is released as chemical energy
60% is released as heat
Cellular Respiration of glucose occurs in what 3 interconnected reaction sequences?
Glycolysis (anaerobic)
Citric Acid Cycle (Aerobic)
ETC/Oxidative Phosphorylation (Aerobic)
Glycolysis and ETC are
stepwise reaction sequences
Citric Acid Cycle occurs in a
cycle; final products reacts to replenish original substrate
Cellular respiration of glucose requires
a supply of glucose and O2
Products of cellular respiration?
CO2
Water
ATP
Heat
Cellular Respiration includes what two reactions?
Aerobic; Require O2, make most of ATP
Anerobic: DO not require O2, and make little ATP
Glycolysis is the first
reaction sequence of glucose breakdown
Glysolysis is a series of
10 reactiosn
Glycolysis breaks down
glucose (6-carbon) into 2 pyruvic acid (3-carbon) molecules
Glycolysis occurs in
cytosol
Glycolysis is in the
anaerobic phase of cellular respiration
Glycolysis yields
2 ATP molecules per glucose molecule broken down
3 Phases of Glycolysis
Phosphorylation of GLucose
Splitting/Cleavage of Glucose into 2 3-Carbon Molecules
Production of NADH, ATP, and 2 Molecules of Pyruvic Acid
Glycolysis; Phase 1
Phosphorylation
Glucose is phosphorylated; 2 APT is used
Glycolysis; Phase 2
Splitting
6-C molecule cleaves into 2 3-carbon molecules
Glycolysis; Phase 3
ATP Formation and Release of Electrons
2 Pyruvic Acid formed
4 ATP Formed
2 NADH and H+ Formed
In presence of O2,
NADH and H+ deliver electrons to the ETC, with oxygen as the final electron acceptor
In absence of O2,
there is no electron acceptor
How is Lactic Acid Formed?
When NADH and H+ deliver electrons and H+ back to Pyruvic Acid
Buildup of lactic acid inhibits
glycolysis, with atp production decreasing
Glycolysis produces much less
ATP than aerobic respiration
In anaerobic reactions, net gain of atp per molecule of glucose?
2
Aerobic Reactions Include
Synthesis of Acetyl Coenzyme A
Citric Acid Cycle
ETC
Aerobic reaction begins with
pyruvic aciid moving from cytosol to mitochondria
Pyruvic acid is used to produce
Acetyl CoA
End products of Aerobic Reaction is
CO2, H2O and up to 36 ATP per molecule of glucose
Citric Acid Cycle begins when
Acetyl CoA combines with oxaloacetic acid to produce citric acid
Citric acid is changed into
oxaloacetic acid thorugh a series of reactions
Citric Acid Cycle repeats as long as
pruvic acid and o2 are available
For each citric acid molecule
1 atp is produced
8 hydrogen atoms are transferred to NAD+ and FAD 2 CO2 are produced
ETC - NADH and FADH2 carry
hydrogen and high energy electrons to the ETC
ETC is a series of
enzyme complexes (electron cariers) located in the inner membrane of mitochondria
ETC- Energy from
electrons is transferred to the enzyme aTP synthase
ETC - ATP synthase
uses energy to catalyze phosphorylation to ADP to ATP
ETC - What is formed?
H2O is formed, with oxygen is the final electron “carrier”
Carbohydrate molecules from foods can enter catabolic pathways
for energy production
carbohydrate molecules from foods can enter anabolic pathways
for storage
carbohydrate molecules from foods can react
to form some of the amino acids
excess glucose can be converted into and stored as
glycogen and fat
Glucose - Glycogen
most cells, but liver and muscle cells store the most
Glucose - Fat
To store in adipose tissue
What is genetic information?
Instructions to tell cells how to construct proteins; stored in DNA sequence
What is a gene?
Sequence of DNA that contains information for making 1 protein
What is a genome?
Complete set of genetic information in cell
What is exome?
Small portion of genome that codes for proteins
What is agene expression?
Control of which proteins are produced in each cell type, in what amount, and under which circumstances
Nucleotides are
building blocks of DNA
Nucleotides consist of
5-carbon sugar, deoxyribose
A phosphate group
A nitrogenous base (A,C, G,T)
Backbone of each strand is a
sugar-phosphate chain
Bases from the 2 complementary strands link together by
hydrogen bonds: C-G, A-T
How are chromosomes formed?
When DNA wraps around histone proteins
Human genome contains
3.2 billion bits of information
What is DNA Replication?
Process that produces an exact copy of a DNA molecules; occurs during interphase
Step 1 in DNA Replication
Hydrogen bond breaks between base pairs
Step 2 in DNA Replication
Strands unwind and separate
Step 3 in DNA Replication
New nucleotides pair with exposed bases, under direction of DNA polymerase
Step 4 in DNA Replication
Other enzymes connect new sugar-phosphate backbone
genetic information store
correct sequence of amino acids for a polypeptide chain
Triplet Code
a sequence of 3 nucleotides that represent an amino acid, or signals beginning or end of a protein
What determines the amino acid sequence in a polypeptide?
Sequences of bases in a gene
Protein synthesis occurs in
cytoplasm
RNA copies and
transfers information from DNA to the cytoplasm
RNA molecules are single
strands of nucleotides
Complementary base pairing in RNA
A-U, C-G
Transcription
Process of copying DNA sequence onto an RNA sequence
mRNA
CArries genetic code from DNA to ribosome
RNA Polymerase
Enzyme that catalyzes the formation of mRNA from the proper strand of DNA
First Step in Transcription of mRNA
RNA polymerase recognizes correct strand of DNA to copy
Second Step in Transcription of mRNA
A section of DNA unwinds to expose the gene coding for the particular protein
Thrid Step in Transcription of mRNA
Complementary mRNA nucleotides pair with the DNA bases (Uracil used instead of Thymine)
Fourth Step in Transcription of mRNA
Termination signal indicates end of gene
Fifth Step in Transcription of mRNA
New mRNA strand is released, and DNA rewinds into double helix
Sixth Step in Transcription of mRNA
The mRNA now leaves the nucleus through a nuclear pore, and attaches to a ribosome in the cytoplasm
What is a codon?
Each amino acid is specified by a sequence of 3 bases in DNA
Protein synthesis occurs in
cytoplasm
mRNA leaves
nucleus and binds to ribosome, to act as template for protein synthesis
At the ribosome, the genetic code, carried by mRNA, is
used to synthesize a protein
What is Translation?
Process of converting the genetic code, carried by mRNA, into a sequence of amino acids that becomes a protein
Protein synthesis requires that
amino acids are added to growing polypeptide chain in proper sequence
tRNA aligns
amino acids during protein synthesis, along the mRNA strand on the ribosome
tRNA binds to
its amino acids, transports it to a ribosome, binds to the mRNA according to its sequence, and adds its amino acid to the growing polypeptide chain
Each tRNA contains
a sequence of 3 nucleotide bases, the anticodon, which binds to complementary codon on the mRNA strand
AS the ribosome moves down the mRNA, each
tRNA brings in its amino cid to be added to the growing protein
How many types of amino acids are there?
20
How many possible codons are there ?
64
What is the initiation codon?
AUG, codes for Methionine, and signals the start of a protein
How many codons are stop codons?
3
Protein synthesis occurs on
ribosomes
mRNA is used as
a template for protein syntehsis
tRNA brings
amino acids to the ribosome, and binds to mRNA, to ad its amino acid to the growing protein chain
Ribosomes are organelles composed of
rRNA and protein molecules
2 unequal subunits
Binding of tRNA and mRNA occurs in
association with a ribosome
Ribosomes move down mRNA molecule, bringing
in tRNAs carrying the proper amino acid to add to the growing protein chain
Amino Acids are joined by
peptide bonds
First step in Translation
A ribosome binds to the mRNA near the codon at the beginning of the messenger strand
Second step in Translation
A tRNA molecule that has the complementary anticodon brings its amino acid to the ribosome
Third step in Translation
A second tRNA brings the next amino acid to the ribosome
Fourth step in Translation
a peptide bond forms between the two amino acids, and the first tRNA is released
Fifth step in Translation
This process repeats for each codon in the mRNA sequence as the ribosome moves along its length, forming a chain of amino acids
sixth step in Translation
the growing amino acid chain folds into the unique conformation of a functional protein
seventh step in Translation
the completed protein molecule is released . The mRNA, ribosome, and tRNAs are recycles
Mutations are
changes in DNA sequence
Mutations occur when
bases are changed, added, or deleted
Mutations can be
spontaneous or induced
Spontaneous Mutation
Due to insertion of unstable base into DNA sequence
Induced Mutation
due to exposure to mutagents, chemicals, or radiation that causes mutation
Duchenne Muscular Dystrophy results from
a muttion in the gene coding for dystrophin; muscle cells collapse, resulting in severe muscle weakness
DNA repair
Correction of mismatched nucleotides by a repair enzyme
