GEN BIO 1 SUMMATIVE 1

Cell

The basic unit of life.

Prokaryotic cell

Cell type with no nucleus.

Eukaryotic cell

Cell type with a nucleus.

Postulates of Cell Theory

States that the cell is the basic unit of life, all organisms are composed of one or more cells, and cells arise from pre-existing cells.

Abiogenesis

The idea that life originates from nonliving matter.

Hans and Zacharias Janssen

Invented the first microscope; a tube with a lens on both sides.

Robert Hooke

Devised one of the earliest microscopes, viewed cork and saw a honeycomb-like structure he called "cellulae," coining the term "Cells."

Antoine van Leeuwenhoek

First person to see live cells; observed animalcules from sampled pond water.

Matthias Schleiden

German botanist who discovered that plants are composed of cells.

Theodor Schwann

German zoologist who discovered that animals are made of cells.

Rudolf Virchow

Proposed "Omnis cellula e cellula," meaning "All cells arise from pre-existing cells."

Aristotle

Earliest recorded scholar to articulate the Spontaneous Generation Theory; proposed life arose from nonliving material containing "pneuma."

Francesco Redi

Disproved spontaneous generation using an experiment with meat in open, corked, and gauze-covered jars, proving maggots come from fly eggs.

John Needham

Supported spontaneous generation after observing microorganisms grow in briefly boiled broth (didn't boil long enough, and air contaminated it).

Lazzaro Spallanzani

Disproved Needham's support for spontaneous generation by boiling broth longer and sealing flasks completely airtight, keeping the broth clear.

Louis Pasteur

Definitively disproved spontaneous generation using his swan-neck flask experiment.

Head (Microscope)

A cylindrical metal tube that holds the eyepiece lens at one end and connects to the nosepiece at the other; also called the body tube.

Arm (Microscope)

Connects the base to the head and eyepiece tube; supports the head and is used when carrying the microscope.

Base (Microscope)

The lowermost part that supports the entire microscope structure; houses illuminators, light switches, and wiring.

Revolving Nosepiece

Holds the objective lenses and allows them to rotate so you can switch magnification levels.

Stage & Stage Clips

Section where the specimen is placed for viewing; clips hold the specimen slide in place.

Fine Adjustment Knob

A smaller knob used to move the stage very slowly, sharpening the image under high power.

Coarse Adjustment Knob

Used for focusing the image under low power magnification.

Eyepiece (Ocular Lens)

Located at the top of the microscope; used to look at the specimen and magnifies the image a second time (usually 10X or 15X).

Eyepiece Tube

The holder for the eyepiece.

Objective Lenses

The lens closest to the specimen, fitted on the nosepiece; types include HPO, LPO, and Oil-immersion.

Illuminator / Mirror

The light source of the microscope; may be a bulb or a mirror reflecting light from an external source.

Condenser

Lenses located under the stage that collect and focus light from the illuminator onto the specimen.

Diaphragm (Iris)

Located under the stage; controls the amount of light reaching the specimen.

Prokaryotes

Cell type comparable to a studio-type condominium unit due to lack of internal compartments; includes all bacteria (Archaea and Bacteria).

Eukaryotes

Cell type comparable to a mansion with several compartments; includes protists, fungi, plants, and animals.

Eukaryote genetic material

Enclosed in the nucleus; more than one linear DNA strand wrapped around histones to form nucleosomes.

Prokaryote genetic material

Located in the nucleoid region; one covalent, closed, circular DNA strand.

Eukaryote chromosomes

More than one chromosome; histones package DNA into nucleosomes and condense it into chromatin.

Prokaryote chromosomes

Only one chromosome plus extrachromosomal DNA called a plasmid.

Eukaryote reproduction

Occurs through mitosis (body cells) and meiosis (sex cells).

Prokaryote reproduction

Occurs through binary fission or spores.

Eukaryote cell wall

Present in most eukaryotic cells (not animals or most protists); made of cellulose (plants) or chitin (fungi).

Prokaryote cell wall

Present in almost all prokaryotic cells; primarily made of peptidoglycan.

Eukaryote membrane sterols

Cholesterol (animals), phytosterol (plants), and ergosterol (fungi).

Prokaryote membrane sterols

Absent, but have a sterol-like lipid component called hopanoids.

Eukaryote ribosome location

Found in the cytoplasm, outer nuclear membrane, rough ER, mitochondria, and chloroplasts.

Prokaryote ribosome location

All found free-floating in the cytoplasm.

Protoplasm

The living matter of the cell.

Eukaryote Cell Wall

A rigid structure surrounding the cell membrane in plant cells, fungi, and some protists; maintains cell shape and prevents bursting.

Cell/Plasma Membrane

The cell's primary barrier and security guard; separates the cytoplasm from the external environment.

Cytoskeleton

Gives the cell its structural framework; facilitates the movement of organelles, macromolecules, and chromosomes.

Phospholipids

Membrane component forming the fluid mosaic bilayer.

Cholesterol (membrane component)

Membrane component that helps regulate membrane fluidity.

Glycolipids

Membrane component made of lipid + carbohydrate; involved in cell recognition.

Head Region (phospholipid)

Contains a phosphate group and is hydrophilic (water-loving).

Tail Region (phospholipid)

Contains two fatty acid chains and is hydrophobic (water-fearing).

Phospholipid Bilayer

Formed by two layers of phospholipids; phosphate heads face the cytoplasm and extracellular environment while fatty acid tails are sandwiched in the middle.

Selective Permeability

Property of the membrane that allows certain molecules to move in and out of the cell; active transport requires ATP for energy.

Permeable substances

Molecules that can cross the lipid bilayer directly: lipids, alcohol, and small molecules like oxygen, nitrogen, carbon dioxide, and water.

Impermeable substances

Molecules blocked by the lipid bilayer: polar molecules and large molecules like glucose, amino acids, nucleic acids, and proteins.

Channel Proteins

Membrane transport proteins that form an open pore for molecules (mostly ions/water) to pass straight through without changing shape; fast but less selective.

Carrier Proteins

Membrane transport proteins that bind to a specific molecule and change shape to shuttle it across; slower but highly specific (e.g. glucose transporters).

Microfilaments

Long fibers of actin protein; the thinnest part of the cytoskeleton; help change cell shape and facilitate cell/organelle movement.

Intermediate Filaments

Provide structural integrity and maintain cell shape; anchor organelles, such as holding the nucleus in place so it doesn't move.

Microtubules

Cytoskeleton component consisting of helically arranged globular proteins called tubulin.

Nucleus (organelle)

The storehouse of genetic information; protects the DNA (contains histones, chromatin, chromosomes, and ribosomes).

Nucleolus

A dense region inside the nucleus that builds ribosomal RNA and assembles it with proteins into ribosomal subunits.

Nuclear Pores

Openings in the nuclear envelope that control what moves between the nucleus and cytoplasm; let RNA/ribosomal subunits out and needed proteins in.

Endoplasmic Reticulum

An interconnected network of thin, folded membranes.

Rough Endoplasmic Reticulum

ER located closer to the nucleus, studded with ribosomes; involved in the synthesis and modification of proteins.

Smooth Endoplasmic Reticulum

ER devoid of ribosomes; involved in lipid synthesis, carbohydrate metabolism, and detoxification.

Golgi Apparatus

Processes, sorts, and delivers proteins transported from the ER; acts as the backbone of the cell's transport system.

Lysosomes

Structures containing chemicals (lysozyme) that break down materials in the cell.

Vacuoles

Storage organelle for water and some weak acids.

Mitochondria

Supplies energy to the cell; has inner folds and compartments for chemical reactions, and possesses its own ribosomes and DNA.

Plastids

Organelles including chloroplasts that convert solar energy into chemical energy; responsible for photosynthesis.

Peroxisomes

Contain enzymes that serve as metabolic assistants to other organelles; involved in synthesizing and breaking down lipids.

Centrosomes

Organelle that serves as the main microtubule-organizing center.

Centrioles

Organelle that helps pull the cell apart during cell division.

Cilia and Flagella

Locomotory projections that allow the cell to move.

Cell/Plasma Membrane

The outer boundary of the cell.

Nucleus

The control center of the cell.

Cytoplasm

Where all the organelles are embedded; composed of cytosol (the fluid area where biological processes happen) and suspended subcellular structures.