Comprehensive Cell Biology & Microscopy: Key Concepts and Techniques

What are the three important parameters of microscopy?

Magnification, Resolution, and Contrast.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.

What are the common features of all cells?

Plasma membrane, Cytosol, Chromosomes, and Ribosomes.

What is the function of the nucleus in eukaryotic cells?

The nucleus houses the cell's genetic material and controls cellular activities.

What is the role of ribosomes in cells?

Ribosomes are responsible for protein synthesis.

What are the two types of endoplasmic reticulum (ER) and their functions?

Smooth ER: synthesizes lipids and detoxifies drugs; Rough ER: has ribosomes for protein synthesis.

What is the function of the Golgi apparatus?

The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

What is the function of lysosomes?

Lysosomes contain enzymes for digestion and waste processing within the cell.

What is the structure and function of mitochondria?

Mitochondria are the energy-converting organelles that produce ATP through cellular respiration.

What is the role of chloroplasts?

Chloroplasts conduct photosynthesis in plants and algae, converting light energy into chemical energy.

What are the three main types of fibers in the cytoskeleton?

Microtubules, Microfilaments, and Intermediate filaments.

What is metabolism?

Metabolism is the sum of all chemical reactions that occur within a living organism.

What are the two types of metabolic pathways?

Catabolic pathways (break down molecules) and Anabolic pathways (build up molecules).

What is the first law of thermodynamics?

Energy cannot be created or destroyed, only transformed from one form to another.

What is the second law of thermodynamics?

In any energy transfer, the total entropy of a closed system will increase over time.

What is ATP and its role in cellular work?

ATP (adenosine triphosphate) is the primary energy carrier in cells, powering various cellular processes.

What is an enzyme?

An enzyme is a biological catalyst that speeds up chemical reactions by lowering the activation energy.

What is feedback inhibition?

Feedback inhibition is a regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme involved in its production.

What is glycolysis?

Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing ATP and NADH.

What is the Krebs cycle?

The Krebs cycle is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA.

What is oxidative phosphorylation?

Oxidative phosphorylation is the process of ATP generation that occurs in the mitochondria, involving the electron transport chain and chemiosmosis.

What are the end products of cellular respiration?

The end products of cellular respiration are carbon dioxide, water, and ATP.

What is fermentation?

Fermentation is an anaerobic process that converts sugars into acids, gases, or alcohol, producing energy without oxygen.

Cells

Basic unit of life

Magnification

Ratio of object's image to real size

Light microscopes

Magnify 1000x

Total magnification

Total mag = objective lens x ocular lens

Electron microscopes

Magnify x 100

Resolution

Being able to clearly see something, seeing two separate points

Contrast

Accentuates differences in parts of the sample

Special lenses

Can use special lenses that provide contrast

Brightfield microscopy

Normal microscope with stained and non-stained lenses

Phase Contrast microscopy

Special lenses with contrast so you don't have to stain it

Fluorescence microscopy

Dyes called flurochromes absorb UV light and re-emit light at a lower (visible) wavelength

Immunofluorochrome

Antibody binds to specific component of cell

Transmission Electron Microscope (TEM)

Electron beam passed through thinly-sliced specimen

Scanning Electron Microscope (SEM)

Electron beams scan surface of specimen

Common Features of All Cells

Membrane (barrier from outside stuff), Cytoplasm, Ribosomes (proteins), DNA but no nucleus

Prokaryotic Cells

Bacteria and Archaea, smaller and simpler without nucleus and no membrane-bound organelles

Eukaryotic Cells

Plants, animals, fungi, protists, larger and more complex because there is a nucleus and contains membrane-bound organelles

Cell Size

Limited by exchange of substances across plasma membrane (PM)

Surface area to volume ratio

Smaller cell has greater SA per V, larger cell has less SA per V

Diffusion

The size relies on diffusion

Growth in multicellular organisms

Relies on increasing cell number, not cell size.

Endomembrane System

Collection of membranes inside and around eukaryotic cells.

Nuclear envelope

Part of the Endomembrane System.

Endoplasmic reticulum

Part of the Endomembrane System.

Golgi apparatus

Part of the Endomembrane System.

Lysosomes

Part of the Endomembrane System.

Peroxisomes

Part of the Endomembrane System.

Vacuoles

Part of the Endomembrane System.

Plasma membrane

Part of the Endomembrane System.

Smooth ER

Involved in lipids, detoxing, and important for gene regulations (calcium ions).

Rough ER

Involved in proteins and contains ribosomes.

Membrane Phospholipids

Selective permeable and are amphipathic - contain hydrophobic and hydrophilic regions.

Fluid Mosaic Model

Describes plasma membranes as fluid with proteins creating a mosaic.

Integral proteins

Embedded in the membrane.

Peripheral proteins

Associated with the membrane surface.

Membrane Carbs

Functions in cell-cell recognition, sorting cells into tissues and organs in embryos, and vary from species to species.

Glycoproteins

Carbohydrates bonded to proteins.

Glycolipids

Carbohydrates bonded to lipids.

Metabolism

Sum of all the chemical reactions in a cell, organized into pathways of chemical reactions.

Thermodynamics

Study of energy transformations.

Chemical energy

Energy stored in chemical bonds, potential energy available for release in chemical reactions.

Entropy

A measure of disorder.

Free Energy

The energy available to do work.

Change in G

Change in free energy (G) = total energy change (H) - temperature in Kelvin units (T) x total entropy change (S).

Spontaneous Processes

A process occurs spontaneously (without energy) when it increases entropy, natural movement toward disorder.

Exergonic Reaction

A reaction with a - change of G that is an energy releasing reaction and is spontaneous.

Endergonic Reaction

A reaction with a + change of G that is an energy-requiring reaction and is not spontaneous.

ATP

Provides energy for endergonic reactions.

Hydrolysis of ATP

Yields 7.3 kcal/mol.

Catalysts

Agents that accelerate a reaction without being altered in the process.

Enzymes

Biological catalysts that bind to substrates to catalyze a reaction.

Substrate

The substance that an enzyme acts upon.

Redox Reaction

Reactions that are chemical resulting in a gain or loss of electrons.

Oxidation

Loss of electrons.

Reduction

Gaining electrons.

Cellular Respiration

Process by which cells break down organic molecules in the presence of O2 - an exergonic reaction.

Metabolic Pathways

Always establish a metabolic disequilibrium to keep the reactions going and to keep the cell alive.

Change of G of 0

Represents death.

Energy Transfer by ATP

ATP energizes reactants by transferring a high energy phosphate to a reactant molecule.

Reaction Rate

10 mil per second.

Chemical Energy in Bonds

Electrons in a polar covalent bond have less chemical energy than those in a non-polar covalent bond.

Electron Carriers

Cellular respiration uses electron carriers to grab high energy electrons from food molecules.

Dehydrogenases

Enzymes that transfer high energy electrons to the electron carriers (coenzymes).

Electron Transport Chain

Carriers donate high energy electrons to an electron transport chain where the energy in the electrons is slowly released and used to make ATP.

Mitochondria

Power house of the cell.

Glycolysis

Means to split glucose, occurs in cytoplasm in the presence or absence of O2.

Energy Investment Phase

2 ATP are used to energize the glucose molecule (phosphates are transferred by kinases).

Energy Yielding Phase

4 ATP and 2 NADH are made as well as 2 pyruvate.

Substrate Level Phosphorylation

A method of generating ATP by directly transferring a phosphate group to ADP.

Transition Reaction

Need to get pyruvate into the mitochondria through transport proteins, and once inside, pyruvate undergoes a chemical change to enter the Krebs cycle.

Krebs Cycle

Completes the breakdown of glucose in the mitochondrial matrix.

Krebs Cycle Outputs

Generates 2 ATP, 6 NADH, and 2 FADH2.

Citric Acid Cycle

Goes around twice per glucose and nets 2 ATP, 6 NADH, 2 FADH2, and 4 CO2.

Electron Transport (Oxidative Phosphorylation)

Chain and Chemiosmosis involving proteins in a line and ATP Synthase in the Inner Mitochondrial Membrane.

Cellular Respiration Efficiency

36 or 38 ATP is only 40% of total energy in a glucose molecule.

Fats vs. Glucose

Fats give you three times the amount of ATP than a sugar molecule.

Effects of Toxins on ETC

Pesticides like rotenone block electron transport at the first ETC protein carrier.