Chapter 6: A Tour of the Cell

Merged flashcards from Chapter 6 of Pearson's Campbell Biology, Twelfth Edition.

Microscope

An instrument used to magnify objects to small to be seen by the naked eye

Light microscope (LM)

A microscope where visible light is passed through a specimen and then through glass lenses, which magnify the image

Magnification

The ratio of an object’s image size to its real size

Resolution

The measure of the clarity of the image

Organelles

The membrane-enclosed structures in eukaryotic cells, such as mitochondria which aids ATP and cellular respiration

• Light microscopy cannot study these due to low resolutions despite staining or labeling

Scanning electron microscopes (SEMs)

Electron microscope that focuses a beam of electrons onto the surface of a specimen, providing images that look 3-D

Transmission electron microscopes (TEMs)

Electron microscope that focuses a beam of electrons through a specimen, used to study internal cell structures

Electron microscopes (EMs)

Microscopes that transmit electrons to view closer details, can be cost prohibitive and includes scanning electron microscopes and transmission electron microscopes

Cell fractionation

The use of centrifuges to fractionate cells into their component parts of organelles, helping determine the functions of organelles based on structure

Prokaryotic cells

Cells have no nucleus, consisting of the Bacteria and Archaea domains

• DNA is contained in the nucleoid

• No membrane-bound organelles

• Cytoplasm bound by plasma membrane

Eukaryotic cells

Cells that do have a nucleus, consisting of protists, fungi, and animals

• DNA in a nucleus bounded by a double membrane

• Membrane-bound organelles

• Cytoplasm in between the plasma membrane and nucleus

• Larger than prokaryotic cells

Plasma membrane

A selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service cells

• Greater sizes require greater surface areas for sufficient nutrients, limiting size

Organelles

Compartments within eukaryotic cells that serve different functions to maintain the overall cell, separated by a membrane of phospholipids and similar between plant and animal cells

Nucleus

Organelle in eukaryotic cells that contains most of the DNA, which is used by ribosomes to make proteins

• One of the most conspicuous organelles

• Separated from the cytoplasm by the nuclear envelope

Nuclear envelope

A double membrane that separates the nucleus from the cytoplasm

Nuclear lamina

Proteins within the nuclear envelope that maintain the shape of the nucleus

Nuclear matrix

A framework of protein fibers throughout the interior of the nucleus

Chromosomes

Discrete units of DNA containing one DNA molecule associated with proteins called chromatin that condenses to form chromosomes during cell division preparation

Nucleolus

Site located within the nucleus for ribosomal RNA (rRNA) synthesis

Ribosomes

Complexes of ribosomal RNA and protein that build protein in the cytosol and on the rough endoplasmic reticulum or nuclear envelope

Free ribosomes

Ribosomes that produce proteins in the cytosol

Bound ribosomes

Ribosomes that produce protein on the outside of the endoplasmic reticulum or on the nuclear envelope

Endomembrane system

System that consists of the:

• Nuclear envelope

• Endoplasmic reticulum

• Golgi apparatus

• Lysosomes

• Vacuoles

• Plasma membrane

Endoplasmic reticulum (ER)

Organelle that accounts for more than half of the total membrane in many eukaryotic cells

• Continuous with the nuclear envelope

• Divided into smooth and rough ER based on ribosomal presence

Smooth endoplasmic reticulum (smooth ER)

Endoplasmic reticulum section that

• does not have ribosomes

• synthesizes lipids

• detoxifies drugs and poisons

• stores calcium ions

Rough endoplasmic reticulum (rough ER)

Endoplasmic reticulum section that

• has bound ribosomes, secreting glycoproteins

• distributes transport vesicles

• creates membrane for the cell

Transport vesicles

Secretory proteins surrounded by membranes

Golgi apparatus

Flattened membranous sacs called cisternae

• modifies products of the endoplasmic reticulum

• makes certain molecules

• sorts and packages materials into transport vesicles

Lysosome

A membranous sac of hydrolytic enzymes that can digest (break down) macromolecules

• Has an acidic environment to support lysosomal enzymes

Phagocytosis

Engulfing another cell for food, creating a food vacuole that is digested by lysosomes

Autophagy

The process in which lysosomes recycle the cell’s own organelles and macromolecules

Vacuoles

Large vesicles derived from the ER and Golgi apparatus

Central vacuoles

Vacuoles found in mature plant cells that contain a solution called sap

• Serves as the plant cell’s main repository of inorganic ions, including potassium and chloride

Mitochondria

The sites of cellular respiration, the metabolic process that uses oxygen to generate ATP found in nearly all eukaryotic cells

• Contains cristae, creating an intermembrane space and mitochondrial matrix with a large surface area

Chloroplasts

The sites of photosynthesis in plants and algae

• Contains the green pigment chlorophyll, as well as other enzymes and molecules functioning in photosynthesis

• Found in leaves and other green organs of plants and algae

Peroxisomes

Oxidative organelles with an unknown lineage

• Bounded by a single membrane

• Contains enzymes that remove hydrogen atoms from various substances to be transferred to oxygen, forming hydrogen peroxide

• Have been found to break fatty acids down for fuel, detoxify alcohol and other harmful compounds in the liver

Cristae

An inner membrane with folds, creating a large surface area for activity

Mitochondrial matrix

Sites where some steps of cellular respiration are catalyzed, presenting a large surface area for enzymes

Thylakoids

Membranous sacs within a chloroplast stacked to form a granum

Stroma

The internal fluid within a chloroplast

Plastids

A group of plant organelles that inlcudes the chloroplast

Cytoskeleton

The support of the cell to maintain shape, interacting with motor proteins to produce cell motility for vesicles and other organelles

Microtubules

The thickest of the three components of the cytoskeleton that help shape the cell, guide organelle movement, and separate chromosomes during cell division

• Also control flagella and cilia beating that project from some cells, where they are sheathed in a plasma membrane extension

Microfilaments (actin filaments)

The thinnest of the three components of the cytoskeleton, forming a cortex inside the plasma to support the cell’s shape

• Makes up the core of microvilli in intestinal cells

Intermediate filaments

Fibers with diameters in a middle range in the cytoskeleton

Pseudopodia

Cellular extensions that allow cells to crawl along a surface

Cytoplasmic streaming

A circular flow of cytoplasm within cells, driven by actin-protein interactions