Download Cellular Metabolism

CELLULAR METABOLISM
Introduction

Cells are the site of metabolic reactions
 Maintain

life
Enzyme: controls each of the reactions
 Specific
type of protein
Metabolic Reactions

Anabolic: building up larger molecules from smaller
ones
 Materials

for cell growth and repair
Catabolic: breakdown of larger molecules into
smaller ones
 Release
energy
Anabolism

Dehydration Synthesis: -OH and –H from separate
molecules are removed forming H2O
 join
sugar molecules into chains forming glycogen
 Triglycerides in adipose cells
 Proteins from amino acids
 Peptide
bonds
Dehydration Synthesis
Catabolism

Hydrolysis: decomposes carbohydrates, lipids, and
proteins
 Splits
water molecules
 C12H22O11
 Sucrose
 Occurs
+ H2O  C6H12O6 + C6H12O6
water glucose
fructose
during digestion
 monosaccharides
 Fats  glycerol + fatty acids
 Proteins  amino acids
 Nucleic acids  nucleotides
 Carbohydrates
Hydrolysis
Control of Metabolic Reactions


Most reaction require energy and a temperature
greater than the body’s
Enzymes promote chemical reactions
 Proteins
 Energy
that lower activation energy
needed to begin a reaction
 Catalysts
 Never
consumed  exist in small quantities
Enzymes

Substrate: particular chemical enzymes act on
 Catalaseenzyme:

hydrogen peroxidesubstrate
Active Site: site on an enzyme where substrate
binds
 Lock
and key
 Very specific
Insulin Degrading Enzyme
Enzyme Reaction

E+S ES  EP  E+P
 S:
Substrate
 E: Enzyme
 P: Product

Reaction Rate increases with increased substrate
concentration
Factors that Alter Enzymes

Denature: protein structure fall apart and becomes
nonfunctional
 Too
high temperatures
 Radiation
 Electricity
 pH changes
 Certain chemicals
 Arsenic
and Cyanides
Denatured Enzyme
ENERGY FOR METABOLIC
REACTIONS
Energy

The capacity to change or move matter;
 Ability
to do work
 Heat
 Light
 Sound
 Electrical
energy
 Mechanical energy
 Chemical energy
Release of Chemical Energy


Chemical energy is held in bonds and released when
bonds are broken
Oxidation: cell burning glucose
 Burning
requires a large amount of energy to begin
 Enzymes
 Most
lower the activation energy
of the energy escapes as light or heat
 Carry
molecules capture about half of the energy
 Remaining energy, heat, help maintain body temperature
Glycolysis




1st step in cellular respiration
Cytoplasm or cytosol
Anaerobic: Doesn’t require
oxygen
Energy is used to synthesize 2
ATP
glucose 2 3-C pyruvic
acid molecules
 6-C
Aerobic Pathway



Requires oxygen
Occurs in the mitochondria
Products: CO2 & H2
 CO2 diffuses
out the cell
 H2 combine with O2 to form H2O

Produces more 34 ATP
ATP vs. ADP

ATP: adenosine triphosphate
3
phosphates
 Fully charged battery
 Break last phosphate off  release energy

ADP: adenosine diphosphate
2
phosphates
 Partially charged battery
 Energy + phosphate  store energy
Metabolic Pathway



Anabolic and catabolic reaction happen in
particular sequence
Enzymes that control the reaction rates must also act
in a specific sequence
Enzymes are positioned in the exact sequence as
that of the reaction
Pathways

Carbohydrates: cellular energy source
 Cellular
respiration
 Glycolysis
 Half

Citric Acid Cycle Electron Transport Chain
of the energy(E)  ATP; remaining E heat
Lipid: phospholipids, cholesterol, triglycerides
 2x
E gram per gram than carb. And protein
 Beta Oxidation: form ketone bodies that can be used in
the citric acid cycle
 Acetone
Protein Pathway

Amino acids are absorb and transported by the
blood to cells
 Amino

acids are reunited into cell parts
Deamination: amino acids have N removed
 Used
in citric acid cycle
 By product: urea
 liver
Metabolic Pathways
Nucleic Acids and Protein
Synthesis
Genetics

In the nucleus, DNA is housed
information from parent to child
 Gene

 instruction

for proteins
Enzymes and control metabolic processes
Karyotype
DNA Molecule


Double Helix
Nucleotides
 Sugar
phosphate backbone
 Nitrogenous bases in the middle
 A,T,G,C
2
strands bonded by H-bonds
A
pairs with T, and G pairs with C
 One
DNA molecule: millions of base pairs long
Genetic Code

DNA: specific nucleotide sequence
 Specifies
a specific amino acid
 RNA molecules transfer information to cytoplasm
RNA



Single stranded
Contain uracil instead of thymine
Contain ribose instead of
deoxyribose
 mRNA:
messenger, carries a copy of
a single gene
 rRNA: composes ribosomes
 tRNA: transfers amino acids
Protein Synthesis

Transcription


Single genes are coped into mRNA
Sent into the cytoplasm to a ribosome
Transcription
Protein Synthesis

Translation




At ribosome, mRNA is read by codons, 3 bases
Amino acids are brought to the ribosome by the tRNA
Anticodons on the tRNA must match the codons on the mRNA
 mRNA: UUA CGC AUC GAU
 tRNA: AAU GCG UAG CUA
Amino acid released from tRNA form a chain and then a protein
DNA Synthesis



Each cell needs a copy of DNA
During interphase, the DNA is replicated
The double helix unzip
 Hydrogen


bonds break
Bases are brought in to each strand
Semiconservative: each DNA molecule contains a
new and an old strand of DNA
DNA Replication