Bios 251 Online Exam 2 Review

Chemical Reactions in the Body

• Metabolism

  • Defined as the sum of all chemical reactions that occur in the body.

  • Two categories of chemical reactions:

  1. Synthesis reactions (Anabolism)

     • Involves the building of molecules from small and simple components into large and complex molecules.

  2. Decomposition reactions (Catabolism)

     • Focus on the breakdown of molecules from large and complex to small and simple components.

Cellular Respiration

• Defined as a set of metabolic reactions that take place in cells.

• Purpose: Converts (breaks down) glucose into energy in the form of Adenosine Triphosphate (ATP).

• Aerobic respiration:

  • Requires Oxygen

Food and Cellular Respiration Process

1. Glycolysis

   • Occurs in the cytosol

   • Converts glucose into pyretic acid, producing ATP and NADH.

2. Krebs Cycle (Citric Acid Cycle)

   • Occurs in mitochondria

   • Processes products of glycolysis to release energy.

3. Electron Transport Chain

   • Uses oxygen to produce ATP from NADH and FADH₂ generated in previous steps.

• Byproducts of respiration:

  • Carbon Dioxide (CO₂) and Water (H₂O)

Cell Structure and Cellular Organelles

• The cell can be divided into 3 parts:

  1. Plasma (cell) membrane: The outer boundary of the cell, controlling what enters and exits. 

  2. Cytoplasm: he gel-like fluid inside a cell that fills the space between the plasma membrane and the nucleus

  • Includes cytosol and organelles (including the nucleus).

  • Nucleus:•The "brain" of the cell, containing most of the cell's DNA. 

Structure of the Plasma Membrane

• Plasma membrane: Defines the boundaries of the cell and serves as a barrier between the cell and its external environment.

  • Intracellular Fluid (ICF): Fluid inside the cell.

  • Extracellular Fluid (ECF): Fluid outside of the cell.

  • Important structure: Phospholipid bilayer.

  • The bilayer consists of:

    • Phospholipids

    • Cholesterol

    • Glycolipids

The Fluid Mosaic Model

• Explanation of the plasma membrane structure:

  • Contains two hydrophobic fatty acid chains attached to a hydrophilic head.

Types of Membrane Proteins

• Integral (Transmembrane) Proteins:

  • Properties: Amphipathic, spanning the entire depth of the plasma membrane, do not dissociate from the membrane.

• Peripheral Proteins:

  • Properties: Located on the outside of the plasma membrane, can easily dissociate from the membrane.

Functions of Membrane Proteins

1. Receptor Proteins

   • Bind to chemical messengers such as hormones sent by other cells.

2. Enzyme Proteins

   • Break down chemical messengers and terminate their effects.

3. Channel Proteins

   • Constantly open, allowing solutes to pass into and out of the cell.

4. Gated Channel Proteins

   • Open and close to allow solutes through at certain times.

5. Cell-identity Marker

   • Glycoproteins distinguishing the body’s own cells from foreign cells.

6. Cell-Adhesion Molecule (CAM)

   • Binds one cell to another.

Selective Permeability of the Plasma Membrane

• The plasma membrane is selectively permeable.

• The bilayer is permeable to small, nonpolar, uncharged molecules.

Functions of the Plasma Membrane

• Guides cell boundaries and defines structural integrity:

  1. Separates ICF and ECF.

  2. Provides structural support and protection for the cell.

  3. Regulates transport of substances in and out of the cell.

  4. Monitors and detects changes in the ECF.

Quiz Questions & Answers

• Gel-like fluid inside a cell:

  • Cytosol.

• Functions of the plasma membrane (multiple choice selections):

  • Defines boundaries of the cell.

  • Provides structural support to the cell.

  • Uses mechanisms to regulate movement of substances.

  • Detects chemical changes in ECF.

• Components of the plasma membrane:

  • Comprised of phospholipids.

Chemical Reactions in Metabolism

• Definitions:

  • Anabolism: Chemical reaction where something is built.

  • Catabolism: Chemical reaction where something is broken down.

  • Metabolism: Sum of all chemical reactions in the body.

Membrane Protein Descriptions

• Integral Proteins:

  • Amphipathic, span entire membrane, usually do not dissociate.

• Peripheral Proteins:

  • Easily dissociate from plasma membrane, found on outside.

Aerobic Cellular Respiration Facts

• Reactants:

  • C_6H_{12}O_6 (glucose) and O_2 (oxygen).

• Products:

  • 6CO_2 (carbon dioxide), 6H_2O (water), and 30 - 32 ATPs.

Steps of Cellular Respiration

• First Step:

  • Glycolysis occurs in the cytosol.

• Krebs Cycle Location:

  • Mitochondrial matrix.

Concentration Gradient Definition

• Defined as the difference in concentration of a chemical across the plasma membrane.

Transport Across the Plasma Membrane

1. Passive Processes (do not require energy):

   • Simple Diffusion: Movement of substances from high to low concentration.

   • Facilitated Diffusion: Similar to simple, but with help from transmembrane proteins.

   • Osmosis: Movement of water from an area of high to low concentration of WATER, not solute.

2. Active Processes (require energy):Moving substances from low to high concentration.

3. Exocytosis: Process of vesicles fusing with the cell membrane to release contents outside the cell.

4. Endocytosis: Including phagocytosis and pinocytosis, entails bringing substances into the cell.

Types of Tonicity

• Hypertonic: More solutes outside than inside; cells shrink.

• Isotonic: Equal solute concentration inside and outside; cells maintain their shape.

• Hypotonic: More solutes inside than outside; cells swell and may burst.

The Cell Cycle Overview

• Phases:

  1. G1 Phase: Cell grows preparing for DNA replication.

  2. S Phase: DNA replication.

  3. G2 Phase: Cells prepare for mitosis.

  4. Mitosis: Actual cell division.

Mitosis Stages

1. Prophase: Chromatin condenses into chromosomes.

2. Metaphase: Chromatids lie along midline of the cell.

3. Anaphase: Sister chromatids separate and move to opposite poles.

4. Telophase: Mitotic spindle disappears, new nuclear envelope forms.

Meiosis Overview

• Definition: Division of sex cells (reproductive cells).

• Process Characteristics:

  • DNA replicated once, divides twice.

  • Results in two haploid cells, each with 23 chromosomes.

Tissue Types

1. Epithelial Tissue:

   • Arranged in sheets, covering body surfaces and lining passageways.

2. Connective Tissue:

   • Diverse; supports, connects, transports, stores.

3. Muscle Tissue:

   • Contracts for movement.

4. Nervous Tissue:

   • Conducts impulses, processes signals.

Epithelial Tissue Details

• Features:

  • Cells characterized by apical (free) and basal (attached) sides.

  • Types based on cell shape: Squamous, Cuboidal, Columnar; layers: Simple, Stratified, Transitional.

Glandular Epithelium Modes of Secretion

• Merocrine glands: Secrete via exocytosis.

• Apocrine glands: Shed apical portion.

• Holocrine glands: Entire cell lost in secretion.

Connective Tissue Characteristics

• Embedded in extracellular matrix made up of:

  • Protein fibers: Collagen, Reticular, Elastic fibers.

  • Ground substance: Viscous fluid.

Muscle Tissue Types

1. Skeletal Muscle: Striated, voluntary.

2. Cardiac Muscle: Striated, involuntary.

3. Smooth Muscle: Non-striated, involuntary.

Nervous Tissue Functionality

• Consists of neurons and neuroglia.

• Neurons transmit impulses; neuroglia provide support and nourishment.

Key Questions

1. What makes up extracellular matrix:

   • Protein fibers, Ground substance.

2. Major fiber types in connective tissue:

   • Collagen, Elastic, Reticular.

Types of Control in Muscle Tissue

• Skeletal: Voluntary.

• Smooth: Involuntary.

• Cardiac: Involuntary.

Summary of Key Concepts

• Cell junctions: Tight junctions (impermeable barriers), Desmosomes (strength), Gap junctions (communication).

• Epithelial membranes: Mucous (protection), Serous (reducing friction), Cutaneous (skin).