AP Biology | Chapter 6 - A Tour of the Cell

Magnification

Ratio of an objects image size to its real size

Resolution

A measure of the clarity of the image

Contrast

Accentuates differences in parts of the sample
ex.) Staining

3 Important Parameters for Microscopes

Magnification, resolution, contrast

Scanning Electron Microscope

Uses electron beams to scan the SURFACE of samples

Transmission Electron Microscope

Used to study the INTERNAL structure of cells

Cell Fractionation

The disruption of a cell and separation of its organelles by centrifugation

Prokaryotic Cells

DNA found in Nucleoid made up of bacteria and archae. Contains cytosol and plasma membrane, ribosomes, and cell wall and flagella but not membrane enclosed organelles or nucleus.

Eukaryotic Cells

DNA found in the nucleus with a double membrane, larger then prokaryotic cells, contains organelle. Made up of Animals, Plants, Protists, and Fungi

Plasma Membrane

Thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surrounding, allows passage of oxygen, nutrients and waste (made up of phospholipid bilayer), have proteins embedded in them

Volume grows disproportionately more than surface area, smaller object has a greater surface area to volume ratio

What happens if a cell grows in size?

Nucleus

Contains genes, found in Eukaryotic Cell enclosed by the nuclear envelope to keep it away from cytoplasm

Nuclear Envelope

Double membrane perforated with pores that control the flow of materials in and out of the nucleus

Pore Complex

Lines the nuclear envelope to regulate the entry and exit of proteins, RNA, and some large complexes of macromolecules

Chromosomes

Found inside the Nucleus and is made up of DNA and carries genetic structure

Chromatin

Combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell

Nucleolus

The organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus. It makes a large and a small subunit which then exits the nucleus through a pore and they combine to make a ribosome

Protein Synthesis Path

DNA provides instructions to make mRNA which is transported via the pores to the cytoplasm, once in the cytoplasm the ribosomes translate the information into the primary structure of a polypeptide

Ribosomes

Made up of rRNA, and carry out protein synthesis; Found either free stuck in the cytoplasm or attached to the ER or nuclear envelope

Endomembrane System

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. Contains plasma membrane, nuclear envelope, ER, Golgi, lysosomes, vacuoles, lysosomes, and vesicles

Vesicle

Small membrane-bound sac that functions in moving products into, out of, and within a cell

Smooth ER

Functions include: synthesis of lipids, metabolism of carbohydrates, detoxification of poisons, and storage of calcium ions

Rough ER

Contains ribosomes on the membrane surface; sythesis of secretory proteins (glycoproteins) specialized cells secrete proteins produced by rough ER ribosomes and membrane production

Glycoproteins

Proteins that have carbohydrates covalently bonded to them and are important for cell to cell interaction providing cell identification

transport vesicles

Vesicles in transit from one part of the cell to another

Golgi apparatus

Stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum

cis face

The "receiving" side of the Golgi apparatus; closer to the ER

trans face

The "shipping" side of the Golgi apparatus; further away from the ER

lysosome

Membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides, work best in acidic environments

phagocytosis

Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell,can help defend the body by destroying invaders

autophagy

A process that describes lysosomes using their hydrolytic enzymes to recycle the cell's own organic material

apoptosis

A type of cell death in which the cell uses specialized cellular machinery to kill itself

vacuoles

Saclike structures that store materials such as water, salts, proteins, and carbohydrates, can also hold poisons so that when predators bite open the vacuole they get poisoned

food vacuoles

Formed by phacogytosis; pinches off of the plasma membrane and encloses a food particle

contractile vacuoles

Saclike organelles that expand to collect excess water and contract to squeeze the water out of the cell

central vacuole

A large, fluid-filled organelle that stores not only water but also enzymes, metabolic wastes, and other materials. Also they can provide support to leaves

Flowchart of Endomembrane System

Nuclear Envelope->ER->Leave as transport vesicles into Golgi->Golgi pinches off vesicles that give rise to other vesicles such as lysosomes->Transport vesicle carries proteins to plasma membrane->Secretion of proteins

What are the differences in structure and function of the smooth and rough ER?

Rough ER has ribosomes giving it a rough appearance; the smooth ER is in charge of lipid synthesis and stores calcium ions, and detoxification of poisons

Describe how transport vesicles integrate the endomembrane system.

Transport vesicles move membranes and substances they enclose between other components to integrate the endomembrane system.

If a protein functions in the ER, but needs to be modified in the ER, what is its path?

mRNA goes out a nuclear pore and gets translated on the ribosome's on the rough ER, then it is carried to the Golgi by a transport vesicle where it is modified and then carried back to the ER by a transport protein where it can perform its cellular function

What role do ribosomes have in genetic instruction ?

Ribosomes translate the genetic message

What is the molecular structure of nucleoli?

It consists of DNA and rRNA as well as proteins from the cytoplasm, the rRNA and proteins are assembled into small and large sub units

Mitochondria

Organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use

Chloroplasts

Organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis

Endosymbiotic Theory

The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism

Mmitochondrial matrix

The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle as well as enzymes used for ATP

Cristae

An infolding of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP. They also give a greater surface area increasing the productivity of cellular respiration

Thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy

Granum

A stack of thylakoids in a chloroplast

Stroma

Fluid surrounding the thylakoid membrane and containing ribosomes and DNA

Plastids

One of a family of closely related plant organelles, including chloroplasts, chromoplasts, and amyloplasts (leucoplasts)

Peroxisome

A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide. Important function is the breakdown of fatty acid molecules

What are two common characteristics of chloroplasts and mitochondria?

Both are involved in energy transformation, and they both have multiple membranes that separate their interiors

Do plant cells have mitochondria?

Yes, plant cells are able to make their own sugar by photosynthesis, but they need mitochondria in order to turn the sugar into energy.

Why aren't mitochondria and chloroplasts part of the endomembrane system?

Neither come from the ER and they are not connected physically or by transport vesicles to organelles of the endomembrane system. Vesicles in the endomembrane system have only single membranes, whereas mitochondria and chloroplasts have two.

Cytoskeleton

A microscopic network of actin filaments and microtubules in the cytoplasm of many living cells that gives the cell shape and coherence

Motor Proteins

Specialized proteins that use energy to change shape and move cells or structures within cells

Microtubules

Hollow tubes of tubulin molecules whose function is maintenance of cell shape, cell motility and organelle movements "tracks for motor proteins to move"

Microfilaments

Two intertwined strands of actin whose function is muscle contraction, cell division, motility and maintenance of cell shape

Centrosome

Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center

Centriole

One of two small cylindrical cell organelles composes of 9 triplet microtubules; main function is to produce cytoskeleton

Flagella

A long cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules, ensheathed in an extension of plasma membrane

Cilia

Short structures projecting from a cell and containing bundles of microtubules that move a cell through its surroundings or move fluid over the cell's surface

Myosin

A type of protein filament that interacts with actin filaments to cause cell contraction. "walks" along the actin filament

Describe shared features of microtubule based motion of flagella and microfilament based muscle contraction.

Both systems involve long filaments that are moved by motor proteins by grip release grip.

How do cilia and flagella bend?

Dynein arms; synchronized bending because they are restricted by bonded proteins

Cilia vs. Flagella

Similarities include:
Cilia and flagella are both auxiliary parts of living cells.
They can both be used for movement.

Differences include:
1.Flagella are longer in size while cilia are shorter.
2.Cilia contributes in the prevention of dust accumulation in breathing tubes by simply creating a thin layer of mucous in the tube while the flagella mainly uses sperm cells to move and propel.
3.Cilia use 'kinesin' which has an ATPase activity that produces energy to perform the movement while the flagella are powered by the proton-motive force by the plasma membrane.
4.Cilia moves like the breast stroke in swimming while the flagella moves in an oar-like style.
5.Cilia are present in multi-cellular organisms and help in moving fluids past an immobile cell while the flagella are mainly found in gametes.

Mitochondria vs. Chloroplasts

Similarities
-Both have double membrane
-Both have inter membrane space
-Both have electron transport chains
-Both involved in ATP
Differences
-Mitochondria generate ATP from Glucose and Chloroplast generate ATP from light energy
-cristae of the mitochondria are continuous with the inner membrane. thylakoids in the chloroplasts are discontinuous with the inner membrane, i.e. thylakoids and inner membrane are separate entities.

Vesicles vs. Vacuoles

Vesicles are transport units and vacuoles are for storage and form from part of the Rough ER. Vesicles are smaller

Primary Cell Wall

A relatively thin and flexable cell wall furthest outside that is first secreted by a plant cell

Secondary Cell Wall

In plants, a strong and durable matrix often deposited in several laminated layers for cell protection and support

Extracellular Matrix

The substance in which animal tissue cells are embedded consisting of protein and polysaccharides. Used instead of a cell wall

Collagen

Structural protein found in the skin and connective tissue

Proteoglycans

A glycoprotein in the extracellular matrix of animal cells, rich in carbohydrate

Plasmodesmada

An open channel in the cell wall of plant through which strands of cytosol connect from an adjacent cell

Gap Junctions

Points that provide cytoplasmic channels from one cell to another with special membrane proteins. Also called communicating junctions.

Tight Junctions

Membranes of neighboring cells are actually fused forming continuous belts around cell to prevent leakage of extracellular fluid

Desmosomes

Specialized junctions that hold adjacent cell together, consist of dense plate at point of adhesion plus extracellular cementing material