Chapter 4 - Metabolic Reactions Flashcards
Metabolism
Sum of all chemical reactions in the body
Cellular Metabolism:
Sum of all chemical reactions
occurring in a cell; metabolic reactions usually occur in
pathways or cycles
What are the 2 types of metabolic reactions?
Anabolism
Catabolism
Anabolism
Small molecules are built into larger ones;
requires energy
Catabolism
Larger molecules are broken down into
smaller ones; releases energy
Anabolism provides…?
Provides materials for maintenance, cellular growth and repair; requires A T P made during
catabolism; example: Dehydration synthesis:
* Smaller molecules are bound together to form larger ones
* H2O produced in the process
* Used to produce polysaccharides, proteins, triglycerides
Catabolism breaks down larger molecules into…?
smaller ones; A T P is produced; Example: Hydrolysis:
* Used to decompose carbohydrates, proteins, lipids
* Uses H2O to split the substances
* Reverse of dehydration synthesi
Enzymes (protein catalysts):
- proteins that cause specific reactions
- Increase rates of chemical reactions
- Lower the activation energy necessary to start reactions
- Each enzyme is specific to a particular substrate
Metabolic Pathways:
- Series of enzyme-controlled reactions leading to formation of a product
- Each new substrate is the product of the previous reaction
- Each step of a pathway is catalyzed by a different enzyme
example of negative feedback
What are the 3 factors that alter Enzymes?
Cofactor
Coenzyme
Denaturation
Cofactor
- Non-protein substance that combines with the enzyme to activate it
- Some help fold active site into proper conformation
- Some help bind enzyme to substrate
- Can be ion, element, or small organic molecule (coenzyme)
Coenzyme
- Organic molecule that acts as cofactor
- Most are vitamins, which are essential organic molecules that humans
must get from their diet
Denaturation
- Inactivation of an enzyme (or any other protein), due to an irreversible
change in its conformation - Results in enzyme being unable to bind to substrate
Energy
- Capacity to change something, or the ability to do work
- Common forms of energy: Heat, light, sound, electrical
energy, mechanical energy, chemical energy - Energy cannot be created or destroyed, but can be
changed from one form to another
Cellular Respiration
- Process that transfers energy from molecules, and makes
it available for cellular use - Most metabolic reactions use chemical energy
Many metabolic processes require…?
Chemical energy, which is stored in ATP
Energy is help in _____ _____ and released when bonds are ______
Chemical Bonds
&
Broken
Oxidation releases _____ from glucose and other molecules, via loss of ____ _____ and their _____
Energy
&
Hydrogen Atoms
&
Electrons
In cells, enzymes lower activation energy needed for
oxidation in reactions of cellular respiration meaning…?
Energy is transferred to ATP:
* 40% is released as chemical energy
* 60% is released as heat; maintains body temperature
ATP (Adenosine Triphosphate):
- Molecule that carries energy in a form the cell can use
- Main energy-carrying molecule in the cell; energy from
ATP breakdown is used for cellular work
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
Cellular Respiration of glucose occurs in 3 interconnected
reaction sequences:
- Glycolysis (anaerobic)
- 2ATP
- Citric acid cycle (aerobic)
- 2ATP
- Electron transport chain/oxidative phosphorylation
(aerobic) - 32 – 34 ATP
Glycolysis and the Electron Transport Chain are stepwise
reaction sequences
Citric Acid Cycle occurs in a metabolic cycle in which the
final product reacts to replenish original substrate
Cellular respiration of glucose requires a supply of glucose
and O2. Final products of cellular respiration
- Carbon dioxide
- Water
- ATP (chemical energy, 40%)
- Heat (60%)
Cellular Respiration includes 2 types of reactions
- Anaerobic reactions: do not require O2, and make little
ATP - Lactic acid production
- Aerobic reactions: require O2, and make most of ATP
Deoxyribonucleic acid (DNA):
- The genetic material
- Molecule that stores information on its sequence of
nucleotides, that instructs a cell to how synthesize certain
proteins
The proteins coded for on DNA function as:
- Enzymes
- Blood proteins
- Structural proteins of muscle and connective tissue
- Antibodies
- Cell membrane components
Double helix:
- Double-stranded molecule, consisting of 2 chains of
nucleotides - DNA resembles ladder twisted into a spiral
- Backbone of each strand is a sugar-phosphate chain
- Bases from the 2 complementary strands are linked
together by hydrogen bonds: C ̶ G, A ̶ T
Nucleotides are…?
building blocks of DNA
Nucleotides consist of…?
- 5-carbon sugar, deoxyribose
- A phosphate group
- A nitrogenous base (adenine, cytosine, guanine, or
thymine)
2 nucleotide chains of the double helix are…?
Antiparallel - point in opposite directions
Complementary Base Pairing:
Bases pair only with
specific (A ̶ T and C ̶ G)
- A and G are purines, and C and T are pyrimidines
- A purine only binds to a specific pyrimidine
- DNA wraps around histone proteins to give double helix
a compact form in chromatin and chromosomes
A sequence of 3 nucleotides provides…?
template for complementary RNA
Each unit of 3 RNA nucleotides represents…?
Genetic Code
Sequence of bases in a gene determines…?
the amino acid sequence in a polypeptide
Each sequence of 3 nucleotides either represents an…?
amino acid or signals to start or stop protein synthesis
Protein synthesis involves processes of…?
Transcription and Translation
Translation
Process of converting the genetic code,
carried by mRNA, into a sequence of amino acids that
becomes a protein
Each amino acid is specified by a sequence of 3 bases in
DNA, called…?
Codons
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
Changes in Genetic Information
99.9% of human genome sequences are the same among all
people
0.1% of the genome that varies among people includes:
* DNA sequences that affect health
* DNA sequences that affect appearance
* DNA base variations that have no observable effects
Mutations
Changes in the DNA sequence
Mutations occur when bases are changed, added, or deleted
Mutations can be…?
Spontaneous: due to insertion of unstable base into DNA
sequence
Induced: due to exposure to mutagens, chemicals, or
radiation that cause mutation
Some mutations are not _____ and do not affect _____
Harmful
&
Health
Many mutations affect health by changing the…?
Amino Acid sequence, resulting in nonfunctional or missing protein
Example: Sickle cell disease is caused by a single
nucleotide substitution; this causes production of abnormal
hemoglobin, which causes change in shape of red blood
cells, in low-oxygen conditions, and extreme pain
Rarely, a Mutation provides an…?
Advantage to Health
Example: A mutation protects some people against HIV;
the receptor to which the virus binds is incomplete
