Exam 2 - Chapter 6 Flashcards
fundamental unit of life
cell
2 types of cells
- prokaryotic : lack a nucleus and other membrane bound structures
- eukaryotic : cells with a membrane bound nucleus and other membrane bound structures
Cell theory
- All organisms consist of one or more cells
- All cells come from the division of preexisting cells
- All cells pass hereditary material to offspring
constraints of cell size
surface are to volume ratio (SA:V)
What is the biological significance of SA:V -volume?
Volume determines demand for:
•Materials
•Energy
•Oxygen
Volume generates:
•Metabolic wastes
•Carbon dioxide
What is the biological significance of SA:V -area?
- Exchange occurs across surfaces
- Dependent upon surface area
- Folding increases surface are
What size are cells?
- Prokaryotic cells range from 0.1 – 5.0μ m in diameter
* Eukaryotic cells range from 10 – 100μ m in diameter
Structures in All Cells
- Plasma membrane
- Cytoplasm
- DNA
- Ribosomes
- Cytoskeleton
Plasma Membrane
the outermost membrane of a cell
•Physically separates a cells external environment from its internal one
•Regulates the crossing of substances into and out of cell
•Composed of phospholipid bilayer and embedded proteins
•Other molecules can be embedded or attached including cholesterol (animals only), glycolipids, glycoproteins
Cytoplasm
- Cytoplasm – jelly-like cytosol with all suspended cell structures
- Cytosol – jelly-like fluid part of cytoplasm
- In eukaryotes, the cytoplasm is the region between the nucleus and the plasma membrane
DNA
- DNA – genetic information carrier for all cells
- Located in the nucleus of eukaryotic cells
- Located in the nucleoid of prokaryotic cells
Ribosome
- Ribosomes – small structures which synthesize proteins
* Composed of rRNA and protein
Cytoskeleton
cell skeleton made of network of interlinking proteins in the cytoplasm
Prokaryotic Cell Structure
- Nucleoid
- Cell wall
- Capsule
- Pili
- Flagella
- Plasmid
Nucleoid
location of most prokaryotic DNA, not enclosed by a membrane
Cell wall
rigid structure outside the plasma membrane, providesprotection, support, and prevents desiccation
Capsule
jelly -like outer coating on the outside of the cell, providesprotection and aids in attachment to surfaces
Pili
protein fiber that look like “hairs”, helps cell attach to surfaces and can help exchange genetic material
Flagella
long, slender structure used for motion
Plasmids
small circular rings of non-chromosomal DNA which canreplicate independently
Eukaryotic Cell Structure
- Nucleus
- Endoplasmic reticulum
- Golgi apparatus
- Vesicles
- Peroxisome
- Mitochondria
- Chloroplasts
- Cytoskeleton
Parts of the Nucleus
- Nuclear envelope – double-membraned outer boundary of the nucleus containing nuclear pores that controls which substances can
- Nucleoplasm – viscous fluid enclosed by the nuclear envelope
- Nucleolus – dense, irregularly shaped region where ribosomal subunits are assembled
- Chromatin – loosely condensed DNA and histone proteins
Ribosomes
- Free ribosomes – suspended in cytoplasm
* Bound ribosomes – attached to outside of rER or nuclear envelope
Endomembrane System
- Nuclear envelope
- Endoplasmic reticulum
- Golgi apparatus
- Vesicles
- Lysosomes
- Plasma membrane
Endoplasmic Reticulum
continuous system of membranous sacs
•Synthesizes lipids and carbohydrates
•Space inside the cisternae is called the lumen or cisternal space
Smooth ER functions:
- Synthesizes lipids and carbohydrates
- Breaks down carbohydrates and fatty acids
- Detoxifies drugs and poisons
- Stores calcium ions
Rough ER functions
- Ribosomes on the surface synthesize proteins
- Packages products in vesicles
- Makes membrane components (phospholipids & glycoproteins)
Golgi Apparatus
stack of flat membrane sacs called cisternae filled with enzymes which functions as the “post office” of the cell
Golgi Apparatus functions
- Modifies proteins from rER
- Manufactures other macromolecules
- Sorts and tags finished products
- Packages the finished products into vesicles
- Some of the vesicles deliver cargo to the plasma membrane, others become lysosomes, others are delivered elsewhere within the cell
cis vs trans face
cisface – receiving end closest to ER
transface – shipping end, “transport” face
Vesicles
small, membrane-enclosed sacs
Vesicles functions
- Transport substances
* Collect and dispose of wastes, debris, or toxins
Types of Vesicles
- Transport vesicles
- Lysosomes
- Vacuoles
Transport Vesicles
carry molecules produced by the cell to their destination within the cell or to the plasma membrane
Lysosomes
vesicles containing hydrolytic enzymes in digestive compartments, made by rER and transferred to the Golgi apparatus
Lysosomes functions
- Hydrolyze proteins, fats, polysaccharides, and nucleic acids
- Phagocytosis – “cell eating”
- Autophagy – “self eating
Vacuoles
fluid filled membranous structure that isolates or disposes of waste, debris, or toxic materials, derived from ER and Golgi apparatus
Types of Vacuoles
- Food vacuoles – delivers or holds food before fusing with lysosome
- Contractile vacuoles – found in many freshwater protists, pumps excess water out of cells
- Central vacuoles – found in most plant cells, stores compounds and water, maintains fluid balance
Peroxisome
small membranous structures that break down fatty acids and amino acids, can detoxify poisons
•Produce hydrogen peroxide which is broken down into oxygen and water
Mitochondria
a double-membraned structure which produces ATP by aerobic respiration, “powerhouse” of the cell
•Contains its own DNA and ribosomes
•Found in nearly all eukaryotic cells (including plant cells)
Mitochondria structures
•Cristae of mitochondria – folds in inner membrane •Matrix of mitochondria – fluid filled space inside inner membrane
Plastids
•Plastids – double-membraned structures that function in photosynthesis, storage, or pigmentation in plant and algal cells
Chloroplasts
specialized plastids for photosynthesis in some protists and plant cells
•Contains its own DNA and ribosome
Chloroplasts structure
- Thylakoids – interconnected membranous sacs inside inner membrane
- Granum – each thylakoid stack
- Stroma – fluid filled space enclosed by inner membrane that surrounds the grana
Cell Wall
•Some eukaryotes have cell walls including plants, fungi, and some protists
Cytoskeleton molecular motor
Movement of and along the cytoskeleton requires a protein that functions as a molecular motor
•These proteins “walk” along microtubules or microfilaments and functionto carry things along the cytoskeleton or to move the cytoskeleton itself
Microfilaments (Actin filaments)
- Narrowest of three protein fibers with a 7nm diameter
- Made of two globular protein intertwined strands made of actin
- Function in maintaining and changing cell shape and in muscle contraction
Microvilli
extensions of the plasma membrane which enclose cytoplasm and microfilaments in some cells which increase SA:V for absorption or secretion
Intermediate Filaments
- Intermediate size with an 8-10nm diameter
- Made of several strands of fibrous proteins wound together
- Function in maintaining cell shape, anchoring cell structures, and providing a permanent framework for the rest of the cytoskeleton
Microtubules
- Thickest of three protein fibers with a 25nm diameter
- Hollow tubes made of α- tubulin and β- tubulin
- Function in maintaining cell shape, providing “track” for movement, and pulling chromosomes during cell division
- Structural elements of centrioles, flagella, and cilia
Microtubule Organizing Center (MTOC)
•Structure from which microtubules emerge
Animal cells have two MTOC’s
•Basal bodies – organize flagella and cilia •Centrosome – organizes spindle fibers
Microtubule Structures
- Cilia – short, movable structures that project from the plasma membrane, function to move fluids over a cells surface
- Flagella – long and slender, propel cells through a surrounding medium
- Both have ring of 9 microtubule doublets surrounding single microtubule center doublet
Endosymbiosis
- Likely origin of eukaryotic cells was through endosymbiosis
- Process where a prokaryotic cell was engulfed by another prokaryotic cell
- Over time the engulfed cell became a dependent part of the host cell
- Likely origin of mitochondria and chloroplasts
