A Tour of the Cells

2 characteristics of prokaryotic cell:

1. Enclosed by a plasma membrane 2. DNA is contained in a region called the nucleoid

The cytoskeleton has three components:

1. Microfilaments 2. Intermediate filaments 3. Microtubules

4 basic features of a cell:

1. Plasma membrane 2. Semifluid substance called cytosol 3. Chromosomes (carry genes) 4. Ribosomes (make proteins)

Eukaryotic cells are up to ___ _____ than prokaryotes. Eukaryotic cells have membrane-enclosed compartments called _______.

10X larger organelles

_____ & _______ are prokaryotes. They have no membrane-enclosed internal compartments.

Bacteria and Archaea

____ _______ are specialized structures that hold cells together: Tight junctions, desmosomes, and gap junctions

Cell junctions

___ ______ ____ limits the amount of resources and waste products that can cross the cell boundary per unit time.

Cell surface area

_____ are small because a high surface area-to-volume ratio is essential.

Cells

_______: Site of photosynthesis—light energy is converted to the energy of chemical bonds. Chloroplasts have a double membrane.

Chloroplasts

_________ allowed eukaryotic cells to specialize and form the tissues and organs of multicellular organism.

Compartmentalization

______: water with dissolved ions, small molecules, and soluble macromolecule.

Cytosol

______ are like "spot welds." Permit materials to move around them in intercellular space.

Desmosomes

______ ______ (ER): network of interconnected membranes in the cytoplasm; has large surface area

Endoplasmic reticulum

______ _____ are secreted to the outside of the plasma membrane. In eukaryotes, extracellular structures have a _____ _____ _____ in a gel-like medium.

Extracellular structures prominent fibrous macromolecule

The ____ ______ is composed of flattened sacs (cisternae) and small membrane-enclosed vesicles.

Golgi apparatus

_____ _____: Tough, rope like protein assemblages, anchor cell structures in place, and resist tension.

Intermediate filaments

________ store starches and fats.

Leucoplasts

_______: Help a cell or parts of a cell to move and determines cell shape.

Microfilaments

_______: Long, hollow cylinders, form rigid internal skeleton in some cells, act as a framework for motor proteins, and can change length rapidly.

Microtubules

______ ______ is selectively permeable barrier, allows cells to maintain a constant internal environment, is important in communication and receiving signal, and often has proteins for binding and adhering to adjacent cells.

Plasma membrane

______: double-membrane organelle found in plants/algae. _____ contain red, orange, and yellow pigments—gives color to flowers.

Plastid Chromoplasts

Two types of cells: _______ & ______

Prokaryotic and eukaryotic

_______ ___ are very small. ______ are single cells but often form chains or clusters. _______ are very successful; and there is a huge diversity of species in the Bacteria and Archaea domains.

Prokaryotic cells Individuals Prokaryotes

______: sites of protein synthesis. Occur in both prokaryotic and eukaryotic cells and have ______ ______ Ribosomes consist of ______ ______ (rRNA) and more than 50 different protein molecule.

Ribosomes similar structure ribosomal RNA

_____ _______ ______ (RER): ribosomes are attached. Newly made proteins enter the RER lumen where they are modified, folded, and transported to other region.

Rough endoplasmic reticulum

______ determines the amount of chemical activity in the cell per unit time.

Volume

Lysosomes also digest cell materials (__________). Cell components are frequently destroyed and replaced by new ones.

autophagy

In the nucleus, DNA combines with proteins to form _____ in long, thin threads called chromosomes. Before cell division, _____ ______, and individual chromosomes are visible in the light microscope.

chromatin chromatin condenses

The ___ _____ receives vesicles (a piece of the ER that "buds" off) from the ER. At the ____ ______, vesicles bud off from the Golgi apparatus and are moved to the plasma membrane or other organelle.

cis region trans region

Mitochondria have two membranes. The inner membrane folds inward to form ______. This creates a large surface area for the proteins involved in cellular respiration reactions. The _____ _____ contains enzymes, DNA, and ribosome.

cristae mitochondrial matrix

In eukaryotes, ribosomes are free in the _____, attached to the endoplasmic reticulum, or inside mitochondria and chloroplasts.

cytoplasm

The _______ : Supports and maintains cell shape, holds organelles in position, moves organelles, involved in cytoplasmic streaming, and interacts with extracellular structures to hold cell in place.

cytoskeleton

Vacuoles in seeds have ____ ____ to hydrolyze stored food for early growth.

digestive enzymes

The ______ ______ includes the plasma membrane, nuclear envelope, endoplasmic reticulum, Golgi apparatus, and lysosome. Tiny, membrane-surrounded vesicles shuttle substances between the various components.

endomembrane system

The outer membrane of the nuclear envelope folds outward into the cytoplasm and is continuous with the _____ _______.

endoplasmic reticulum

______: collect and break down toxic byproducts of metabolism such as H2O2, using specialized enzymes. _______: only in plants—lipids are converted to carbohydrates for growth

eroxisomes Glyoxysomes

Eukarya are _____: cells with membrane-enclosed compartments called ________. DNA is in a compartment called the ______.

eukaryotes organelles nucleus

The _____ _____: Holds cells together in tissues, contributes to properties of bone, cartilage, skin, etc., filters materials passing between different tissues, orients cell movements in development and tissue repair, and plays a role in chemical signaling.

extracellular matrix

Many animal cells are surrounded by an extracellular matrix, composed of _____ _____ such as collagen, gel-like proteoglycans (glycoproteins), and other proteins.

fibrous proteins

In the mitochondria, energy in _____ ______ is transformed to the bonds of energy-rich ATP (cellular respiration). Cells that require a lot of energy have many mitochondria.

fuel molecules

The motor protein ______ moves vesicles or organelles from one part of a cell to another. It binds to a vesicle and "walks" it along by changing shape.

kinesin

In some cells, microfilaments form a ______ just inside the plasma membrane. This provides structure, for example in the microvilli that line the human intestine.

meshwork

Cilia and eukaryotic flagella are made of ______. ______—short, usually many present, move with stiff power stroke and flexible recovery stroke. ______—longer, usually one or two present, movement is snakelike.

microtubules Cilia Flagella

The nucleus is surrounded by the _____ _____. Many ____ control the movement of molecules across the envelope.

nuclear envelope pores

Specific chemical reactions occur in other ______. This "______ ___ _______" was important in the evolution of complex organism.

organelles division of labor

The ______ _____ is the outer surface of every cell and has more or less the same structure in all cells. It is made of a ______ _______ with embedded proteins and other molecule.

plasma membrane phospholipid bilayer

Adjacent plant cells are connected by plasma membrane-lined channels called ________.

plasmodesmata

The Golgi apparatus receives _____ from the RER—can further modify them, Concentrates, packages, sorts protein, in plant cells, ______ for cell walls are synthesized here.

proteins polysaccharides

In prokaryotic cells, _______ float freely in the cytoplasm.

ribosomes

Most prokaryotes have a _____ ____ _____ outside the plasma membrane.

rigid cell wall

Grana are stacks of ______ —circular compartments of the inner membrane. Thylakoids contain ______ and other pigments that harvest light energy for photosynthesis. _______—fluid in which grana are suspended. The stroma contains DNA and ribosomes.

thylakoids chlorophyll Stroma

The nucleus is usually the largest organelle. Contains the ___, site of DNA ______, site where _____ ________ is turned on or off, assembly of the ribosomes begins in a region called the ______.

DNA replication site transcription nucleolus

______ _____ _____: Cellulose fibers are embedded in other complex polysaccharides and proteins.

Plant cell walls

Plant cell walls may have multiple layers: _____ _____ ____: relatively thin and flexible. _____ _____: thin layer between primary walls of adjacent cells. ____ _____ ______: (in some cells): added between the plasma membrane and the primary cell wall.

Primary cell wall Middle lamella Secondary cell wall

_____ ______ originate from the Golgi apparatus. They contain _____ _____ which hydrolyze macromolecules into monomers.

Primary lysosomes digestive enzymes

_____ ______ help ensure directional movement of materials. Bars the movement of dissolved materials through space between cells.

Tight junctions

Food molecules enter the cell by _______ —a phagosome is formed. ______ fuse with primary lysosomes to form secondary lysosomes. Enzymes in the secondary lysosome hydrolyze the food molecules.

phagocytosis Phagosomes

Plant and protist cells have _____, which stores waste products and toxic compounds; some may deter herbivores, provide structure for plant cells—water enters the vacuole by osmosis, creating turgor pressure, and store pink and blue pigments in flowers and fruits; the colors attract pollinator.

vacuoles