BIOL 110 Chapter 4 Study Guide

Cell Theory

Cells are the smallest units of life; new cells come only from pre-existing cells by cell division.

Resolution

Ability to observe two adjacent objects as distinct from each other (how clear the image is).

Contrast

How different one structure looks from another, and can be enhanced by special dyes to reveal cellular structure.

Magnification

Ratio between the size of an image produced by a microscope and its actual size.

Light Microscope

Uses light for illumination and has a resolution of 0.2 micrometers.

Electron Microscope

Uses a beam of electrons for illumination and has a resolution of 2 nanometers.

Scanning Electron Microscope (SEM)

Sample coated with heavy metal and beam scans surface to make a 3D image.

Transmission Electron Microscope (TEM)

Beams of electrons transmitted through sample, and thin slices of the sample are stained with heavy metals, forming an image.

Standard (bright field) Microscopy

Light is focused with glass lenses and goes directly through the sample (can be with or without dyes).

Phase Contrast Microscopy

Microscope amplifies differences in phase of light transmitted or reflected by sample and has improved contrast of denser structures.

Differential Interference Contrast

Another method using optics to improve contrast and is good for internal cellular structures.

Features of all cells

Cell membrane

-Cytoplasm (semifluid substance)

-DNA in a long chromosome

-Ribosomes (makes proteins).

Prokaryotes

Have simple structure and no nucleus.

Bacteria

Small cells that are very abundant in the environment and the majority are not harmful to humans (some species cause disease).

Archaea

Small cells that are less common and are often found in extreme environments (ex. hot spring).

Eukaryotes

More complex cells with DNA enclosed within the membrane bound nucleus, has internal membranes that form organelles, compartmentalized functions, and variety in shape, size, and organization of cells.

Cell Morphology

Size and shape of eukaryotic cells show great variation (even cells that share the same genome can have very different morphologies).

Cytosol

Region of a eukaryotic cell that is outside the cell organelles but inside the plasma membrane (region for metabolic activities).

Cytoplasm

Includes EVERYTHING inside the plasma membrane.

Endomembrane System

Network of membranes enclosing the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles (and includes the plasma membrane).

Nucleus

Contains the genome, chromosomes (DNA and proteins = chromatin).

Nucleolus

Located within the nucleus and is the site of ribosome assembly (proteins and RNA molecules enter the nucleolus and are assembled and sent back out in subunits).

Nuclear Envelope

Has a double-membrane structure, and nuclear pores where inner and outer nuclear membranes contact each other.

Nuclear Matrix

Nuclear lamina and an internal nuclear matrix (filamentous network that organizes chromosomes into distinct chromosome territories).

Ribosomes

Make proteins and are ribosomal RNA and protein (carry out protein synthesis in the cytosol or are bound to the endoplasmic reticulum).

Endoplasmic Reticulum

Network of membranes that form flattened, fluid-filled tubules or cisternae.

Rough ER

Has bound ribosomes, attaches carbohydrates to proteins (glycosylation), packages proteins into membrane vesicles, is a membrane factory.

Smooth ER

Synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores Calcium ions.

Golgi Apparatus

Consists of flattened membranous sacs called cisternae, modifies products of the ER, manufactures certain macromolecules, and sorts and packages materials into transport vesicles.

Lysosomes

A membranous sac of hydrolytic enzymes that can digest macromolecules (proteins, carbohydrates, nucleic acids, lipids).

Vacuoles

Functions are extremely varied, and they differ among cell types and environmental conditions.

Central Vacuole

Vacuole in plants for storage and support

Contractile Vacuole

Vacuole in protists for expelling excess water

Phagocytic Vacuole

Vacuole in protists and white blood cells for degradation

Peroxisomes

Catalyze certain reactions that break down molecules by removing hydrogen or adding oxygen (hydrogen peroxide is a byproduct, and catalase breaks down dangerous hydrogen peroxide into water and oxygen).

Plasma Membrane

Membrane transport with selective permeability with cell signaling using receptors and cell adhesion.

Mitochondria

Primary role is to synthesize ATP; outer and inner membrane creates two compartments (intermembrane space and the mitochondrial matrix). Derived from purple bacteria. Involved in synthesis, modification and breakdown of cellular molecules.

Chloroplasts

Photosynthesis; found in nearly all species of plants and algae (not common or part of animal cells). Have a third membrane (thylakoid membrane) which forms flattened tubules that stack to form a granum.

Cytoskeleton

Network of three types of protein filaments.

Microtubules

Long, hollow cylindrical structures with dynamic instability (filaments come out of the centrosome and found in cilia and flagella).

Intermediate Filaments

Intermediate in size, form twisted, rope-like structure.

Actin Filaments

Also known as microfilaments, long thin fibers.

Flagella

Usually longer than cilia and present singly or in pairs, made of microtubules.

Cilia

Shorter than flagella and made of microtubules.

Motor Proteins

Use ATP as a source of energy to promote movement (they move vesicles along microtubules, which causes a filament to slide, and causes the flagella and cilia to bend and move muscles).