Chapter 4: Cells

finished chapter in lecture 9/6. Finished flashcards 9/8

Cell theory

All living things are made of cells that share some common characteristics (basic shape, internal content, dna chromosomes, metabolic capabilities)

What cells are present in animals, plants, fungi, and protists?

eukaryotic cells

What cells are present in bacteria and archaea?

Prokaryotic cells

Describe the difference between light microscopes and electron microscopes.

Light microscopes use light to illuminate the specimen. Electron microscopes use electrons to illuminate the specimen

cell size is limited by

surface area to volume ratio

fluid mosaic model

phospholipid bilayer with embedded proteins

Cytoplasm, cytosol, cytoskeleton

cytoplasm is between the plasma membrane and the central region, contains the cytosol and cytoskeleton.

cytosol is an aqueous solution containing ions, organic molecules, and organelles

cytoskeleton maintains cell shape and plays key roles in cell division

Nucleus in prokaryotic vs eukaryotic cells

eukaryotic cells have a true nucleus separated from the surrounding cytoplasm by membranes.

prokaryotic cells have a nucleoid region without a boundary membrane

DNA in prokaryotic cells

Typically a single circular molecule

Bacterial arrangements is dependent on

pattern of division and how cells remain attached after division

Plasma membrane in prokaryotic cells is surrounded with

Surrounded by a rigid cell wall coated with polysaccharides (glycocalyx)

Functions of the glycocalyx

protect cells from dehydration and nutrient loss

inhibit killing by white blood cells by phagocytosis

attachment (formations of biofilms)

What is the cell envelope?

External covering outside the cytoplasm, containing two basic layers: cell wall and cell membrane.

It maintains cell integrity

Peptidoglycan

determines cell chape and prevents lysis due to changing osmotic pressures, linked by polypeptides. forms a mesh-like surrounding to bacteria

Gram-positive cell wall

thick homogeneous sheath of peptidoglycan, includes teichoic acid and lipoteichoic acid. May have a periplasmic space between the cell membrane and cell wall

Gram negative cell wall

a thin layer of peptidoglycan between the outer and inner membrane of a cell

flagella are anchored in

the cell wall

How do flagella move

rotates 360 degrees

Prokaryotic genetic material

chromosome - usually single, circular double stranded DNA molecule that contains all the genetic info required by a cell (clumped in nucleoid)

Plasmids (extra-chromosomal DNA) possible. may encode antibiotic resistance and other toxins, not essential to bacterial function

Ribosomes made of 60% ___ and 40% ___

ribosomal RNA, protein

Ribosomal subunits

Large and small. Prokaryotic and eukaryotic ribosomes differ in size and number of proteins

Ribosome function

protein synthesis

A coating or layer of molecules external to the cell wall. It serves protective, adhesive, and receptor functions. It may fit tightly or be very loose and diffuse.

Glycocalyx

composed of condensed DNA molecules. DNA directs all genetics and heredity of the cell and codes for all proteins.

Bacterial chromosome or nucleoid

Double-stranded DNA circle containing extra genes

Plasmid

An elongate, hollow appendage used in transfers of DNA to other cells

Pilus

Tiny particles composed of protein and RNA that are the sites of protein synthesis

Ribosomes

Long fibers of proteins that encircle the cell just inside the cell membrane and contribute to the shape of the cell

Actin cytoskeleton

Specialized appendage attached to the cell by a basal body that holds a long, rotating filament. The movement pushes the cell forward and provides motility.

Flagellum

Fine, hairlike bristles extending from the cell surface that help in adhesion to other cells and surfaces

Fimbriae

Stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed.

Inclusion/Granule

A semirigid casing that provides structural support and shape for the cell

Cell wall

A thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool

Cell (cytoplasmic) membrane

Extra membrane similar to cell membrane but also containing lipopoly saccharide. Controls flow of materials and portions of it are toxic to mammals when released.

Outer membrane

Dormant body formed within some bacteria that allows for their survival in adverse conditions

Endospore

Water-based solution filling the entire cell

cytoplasm

What are Archaea?

Prokaryote, similar to bacteria - circular DNA genome in a nucleoid region with no nuclear envelope. No membrane-bound organelles.

Also shared features with eukaryotes - may share a common ancestral line with eukaryotes.

Phylogenetic Tree of Life

Shows the branches of each type of cell in three domains: bacteria, archaea, eukarya

Endosymbiotic theory

eukaryotes evolved from prokaryotic organisms (and organelled originated from trapped prokaryotic cells)

Which organelles are present in animal cells but not plant cells?

Centrioles, lysosomes, cilia

Organelle for energy metabolism

Mitochondrion

Membrane-bound organelle containing enzymes for digestion of many complex molecules

Lysosome

Cytoskeleton component consisting of tubulin; anchor various organelles and provide tracks for vesicle movement

Microtubules

Membraneless organelle near the nucleus where microtubules are formed and radiate outward; contains a pair of centrioles

Centrosome

Small membrane-bound compartments that transfer substances between various membranous sacs in the cell, such as the endoplasmic reticulum and golgi complex

Vesicle

Responsible for modification, distribution of protiens

Golgi complex

Aqueous solution of cytoplasm containing ions and organic molecules

Cytosol

Lipid bilayer membrane that bounds the cell; contains embedded proteins for transport of substances into and out of cell, and for receiving cellular signals

Plasma membrane

A cytoskeleton component consisting of actin; involved in a number of structural and locomotory functions

Microfilaments

Synthesis, modification, and transport of proteins

Rough ER

Synthesis of proteins

Ribosomes

What are the two locations of ribosomes in the cell?

Attached to the rough ER

Free in cytosol

Synthesis of lipids for membranes

Smooth ER

Membrane-enclosed region of DNA; hereditary control

Nucleus

Controls exchange of material between nucleus and cytoplasm

Nuclear pore complex

Double lipid bilayer membrane that separates nucleus from cytoplasm

Nuclear envelope

Complex of DNA hereditary material and protein

Chromatin

Formed around rRNA genes; rRNA synthesis and ribosome assembly

Nucleolus

Organelles present in plant cells but not animal cells

Cell wall (with plasmodesmata)

Chloroplasts

Central vacuole

Central vacuole membrane, present only in plant cells.

Tonoplast

Cell growth, support, and storage; contains enzymes for digestion of many complex molecules. present only in plant cells.

central vacuole

Photosynthesis; some starch storage

Chloroplasts

Channels through cell wall. Present only in plant cells

Plasmodesmata

Protection, structural support in plant cells

Cell wall

proteins to be imported into the nucleus have a special, short amino acid sequence called a

nuclear localization signal

Liquid within the nucleus is called

nucleoplasm

DNA in eukaryotes

linear

Eukaryotic cells have an ____ that divides the cell into functional and structural compartments

endomembrane system

The endomembrane system includes the nuclear envelope, plasma membrane, and which organelles? (4)

endoplasmic reticulum, golgi complex, lysosomes, vesicles

Describe the path of a protein

proteins synthesized either on the ER or in free ribosomes → enter ER membranes

proteins modified in ER → vesicles bud from ER membrane and transport to Golgi

vesicles from ER bind to cis end of Golgi → modification and sorting → vesicles bud from trans end

Secretory vesicles can take proteins from Golgi to the plasma membrane for release. Lysosomes can digest damaged organelles or contents of vesicles.

The breaking down of bacteria or other cellular debris in lysosomes

Phagocytosis

pH in lysosomes is (basic/acidic)

acidic

Cellular respiration occurs in

mitochondria

The process by which energy-rich food molecules are broken down to water and CO₂ , and energy is captured in ATP

cellular respiration

Parts of the mitochondria

Outer mitochondrial membrane covers the organelle

Inner mitochondrial membrane is expanded by folds called cristae

The innermost compartment = mitochondrial matrix (contains DNA, ribosomes, and other components)

Where in mitochondria do ATP generation reactions occur?

In the cristae and matrix

How do eukaryotic flagella and cilia move?

They whip back and forth

colorless plastids that store starch in plant cells

Amyloplasts

Parts of a chloroplast

inner and outer boundary membrane around the stroma (fluid interior).

Within the stroma is a third membrane system of flattened, closed sacs (thylakoids)

when thylakoids are stacked → grana

Chlorophyll stored in thylakoid membranes

cell adhesion molecules

bind cells together

cell junctions

seal the spaces between cells and provide direct communication between cells

Extracellular matrix

supports and protects cells and provides mechanical linkages between tissues

glycoproteins in the plasma membrane that bind to specific molecules on other cells

cell adhesion molecules

__ are the main component of extracellular membrane

Glycoproteins. In animals, collagen