Biology 1 Exam 2

What is energy? Types?

The ability to do work

Kinetic- movement E

Potential- stored E

1st Law of Thermodynamics and how it affects animals

Energy cannot be created nor destroyed (only transformed)

Meaning, animals must obtain E from food. They are converters not creators.

2nd law of thermodynamics

Every energy transfer increases entropy (disorder)

Meaning, animals constantly lose E as heat during metabolism

Eltonian Pyramid

shows E flow trhough trophic levels. E decreases at each level

Metabolism

all chemical reactions in a cell

Catabolism

breaks molecules (releases E)

Anabolism

builds molecules (uses E)

Base Metabolism

Minimum E needed for basic life processes

Enzyme Definition + Function

Biological catalysts made of protein. Speeds up reactions by lowering activation energy

Activation Energy

E required to start a reaction

Feedback inhibition

End product inhibits an earlier enzyme to regulate the pathway (prevents waste)

ATP

structure: adenine + ribose + 3 phosphate groups

function: main E currency of cell

formed mostly in the mitochondria during cellular respiration

Glycolysis - Phase 1

glucose + ATP <-> G6P + ADP <-> F6P + ATP <-> F1, 6DP + ADP <-> 2 G3P

down 2 ATP

Glycolysis - Phase 2

x2 [G3P + NAD <-> 1,3DPG + NADH + 2 ADP <-> 3PG + ATP <-> 2PG <-> 2 PEP + H2O + ADP <-> pyruvate + ATP]

2 ATP (phase 1)

+ 4 ATP (phase 2)

-------------------

+2 ATP

Pyruvate oxidation (mitochondria)

x2 [pyruvate + NAD + CoA <-> acetyl CoA + CO2 + NADH]

Krebs/citric acid cycle (mitochondria)

x2 [acetyl CoA + oxaloacetate + 3NAD + FAD + ADP <-> oxaloacetate + 3 NADH + FADH2 + ATP + 2CO2]

ETC

x2 [ NADH <-> NAD + H + E -> 3 ADP + 3P + E <-> 3 ATP = 18 ]

x2 [ FADH2 <-> FAD + H2 + E -> 2 ADP + 2P + E <-> 2 ATP = 4 ]

Different fuels:

carbs -> easiest; enter at glycolysis

fats -> broken into glycerol + fatty acids (enter @ various steps)

proteins -> amino acids deaminated -> enter @ K

anaerobic respiration

Glucose <-> 2 pyruvate <-> fermentation (lactic acid)

+ 2 ATP per glucose

Interphase

G1: normal

S: DNA replication

G2: preparation for division

Mitosis

Prophase- chromosomes condense and spindle fiber forms. Nuclear envelope disintegrates

Metaphase- chromosomes align at the equator of the cell

Anaphase- sister chromatids pulled apart

Telophase- nuclear envelope reforms. Gets rid of spindle fibers

Cytokinesis

cytoplasm divides ( cleavage furrow )

Control and checkpoints:

controlled by cyclins and CDKs

checkpoints ensure DNA is undamaged

Specifics @ Checkpoints:

G1: checks DNA. If damaged, it tries to fix it. If it can't, apoptosis occurs.

G2: checks to make sure DNA replicated properly. If damaged, it tries to fix it. If it can't, apoptosis occurs.

M: spindle fiber assembly checkpoint. If damaged, it tries to fix it. If it can't apoptosis occurs.

M is located specifically at the metaphase part of mitosis.

Bacterial Division

binary fission: simpler, no nucleus, no mitosis

Cancer

unregulated cell growth due to mutations in DNA

Causes of cancer:

Carcinogens ( UV, tobacco, radiation, etc)

Genetic predisposition

Viral infections

Are all mutations cancerous?

No - all cancer is caused by mutations, but not all mutations cause cancer.

Can one mutation cause cancer?

rarely. usually multiple mutations accumulate

Predisposed to Cancer

Means an inherited gene increases the risk, but environment still plays a role.

Benign Tumors

do not spread but can crowd out surrounding cells

Malignant Tumors

can spread and cause secondary tumors.

Metastasis

Spread of cancer to new areas

Angiogenesis

Formation of new blood vessels to feed tumor

Chemotherapy

Drugs that target fast-dividing cells. Really harsh on the body and kills everything

Radiation Therapy

Destroys cancer cellls' DNA

Oncogens

Mutated genes that cause cancer