biology exam #3

exergonic

• Releases energy

• Happens spontaneously

• Example: breaking down sugar

• ∆G < 0 → a reaction is spontaneous or doesn’t require input of energy to occur 

Catabolic

• Breaks large molecules into smaller ones

• Often releases energy

• Example: digesting food

• ∆G > 0→ a reaction requires energy input to occur 

• Are usually exergonic

Anabolic

• Builds larger molecules from smaller ones
  

• Needs energy input
  

• Example: building muscles

• Most anabolic reactions are endergonic

endergonic

• Requires energy
  

• Not spontaneous
  

• Example: photosynthesis

First law of thermodynamics

• energy cannot be created or destroyed, but can be transferred or transformed

2nd law of thermodynamics

• when energy is transformed or transferred, some amount can f energy is lost as heat

potential energy

• energy in an object that is NOT moving

Chemical energy

• the potential energy stored in chemical bonds

Kinetic energy

• energy in an object that IS moving

Thermal energy

• the kinetic energy of molecules / small particles

Activation energy

• small amount of energy needed to start a chemical reaction

Enzymes

• proteins that speed up reactions

• Have a specific shape with an active site
  

• Induced fit = enzyme slightly changes shape to fit substrate
  

• Enzymes lower activation energy, making reactions faster and easier

Active site

• a pocket on the enzyme—> spot where the enzyme grabs onto the molecule it works on

Substrate

• the molecule the enzyme works on —> fits into enzymes active site

allosteric enzymes

• can be turned off or on by other molecules

Competitive inhibition

• Inhibitor competes with substrate for active site
  

• Blocks substrate from binding

Noncompetitive inhibition

• Inhibitor binds elsewhere on enzyme
  

• Changes enzyme’s shape → substrate can’t fit

Normal bindings

• if the substrate and it’s enzyme are both present, they will bind together at the active site

Allosteric inhibitor

• when it binds, this will stabilize the inactive form of the enzyme

Feedback inhibition

• when the end produce of a series of reactions inhibits the first enzyme, shutting down that pathway

1. Cell uses enzymes to make a product

2. Too much product builds up

3. Product “feeds back” and binds to an early enzyme

4. Enzyme shape changes → pathway stops ✅ Saves energy!

Cellular respiration equation

• Glucose + oxygen → carbon dioxide + water + ATP
  

• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

The Gradual Harvesting Of Energy from Glucose:

1. Glycolysis

2. Pyruvate oxidation

3. Citric acid cycle

4. Oxidative phosphorylation

majority of ATP is made where?

Oxidative phosphorylation

What causes fermentation

When no oxygen is available

Photosynthesis equation

• Carbon dioxide + water + sunlight → Glucose + oxygen
  

• 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

Light dependent reaction

• Location: Thylakoid
  

• Needs sunlight
  

• Water split → O₂ released
  

• Makes ATP + NADPH

Calvin Cycle

• Location: Stroma
  

• Uses ATP + NADPH
  

• Fixes CO₂ → builds glucose

• Input: CO2

• Output: G3P (sugar), NADP+, ATP, phosphate ion

Stages of Calvin Cycle

1. Carbon Fixation – CO₂ joins RuBP

2. Reduction – ATP/NADPH → G3P

3. Regeneration – G3P → RuBP

Describe the interphases

• Interphase:
  

  • G1: Cell grows

  • S: DNA is copied

  • G2: Final checks and prep
    

• Mitotic (M) Phase:
  

  • Mitosis → nucleus divides

  • Cytokinesis → cytoplasm splits

Stages of Mitosis

1. Prophase

2. Prometaphase

3. Metaphase

4. Anaphase

5. Telophase

6. Cytokinesis

Prophase

• Chromosomes condense, spindle forms

Prometaphase

• Nuclear envelope breaks, spindles attach

Metaphase

• Chromosomes line up

Anaphase

• Sister chromatids pulled apart

Telophase

• Nuclear membranes reform

Cytokinesis

• Two cells form

G0 Phase

• If a cell doesn’t get right signals to proceed into S Phase, it goes into G0 phase

• Non growth phase

Apoptosis

Programmed cell death

Chromatin

Loose, tangled DNA

Chromosomes

Coiled DNA (more visible when dividing)

Sister chromatids

• Identical copies joined together of a single chromosome

Homologous chromosomes

• One from mom, one from dad – similar but not identical

Mitosis

• Only one round

• Produces 2 identical daughter cells

• Start from diploid cell, end with 2 diploid clones

Meiosis

• 2 sounds: Meiosis I and Meiosis II

• produces 4 genetically unique daughter cells Start

• Start from diploid cell, end with 4 haploid gametes

Describe each phase of Meiosis

• Meiosis I: homologous chromosomes separated into 2 haploid cells

  • Prophase:

  • Metaphase

• Meiosis II: sister chromatids in the 2 haploid cells are separated and the end results is 4 haploid cells

  • Prophase II

  • Metaphase II : sister chromatids are not identical like at the start of Meiosis I

  • Anaphase II: sister chromatids are separate by breaking of centromere

  • Telophase II : 4 genetically unique daughter cells are produced