Cellular structure and function (unfinished)

Light microscopy

visible light is passed through a specimen and then through glass lenses. Lenses refract (bend) the light, so the image is magnified about 1000x.

Most subcellular structures are ____ to be resolved by an LM

too small

What do scanning electron microscopes (SEMs) do

focus on a beam of electrons onto the surface. Makes 3d image

Transmission electron microscopes (TEMs)

focus a beam of electrons through a specimen. Better for internal structure of electrons

Cell fractionation definition

takes cells apart and separates the major organelles from one another

Cell fractionation function

Centrifuges fractionate cells into their component parts. Enables scientists to determine the function of organelles

Centrifuge speeds to components

lower speeds, larger component pellet: higher speeds, smaller components pellet

Eukaryotic cells have ____ that compartmentalize their functions

internal membranes

Prokaryotic domains

bacteria, archaea

Eukaryotic kingdoms

protists, fungi, animalia, plantae

Basic features of cells

plasma membrane, Semifluid substance called cytosol, chromosomes (carry genes), ribosomes (make proteins)

Prokaryotic vs eukaryotic DNA location

Prokaryotic - unbound region called the nucleoid. Eukaryotic - In a nucleus bounded by a membranous envelope

Prokaryotic vs eukaryotic membrane bound organelles

Prokaryotic - no. Eukaryotic - yes

Prokaryotic vs eukaryotic cytoplasm

Prokaryotic - bound by the plasma membrane. Eukaryotic - in the region between the plasma membrane and nucleus

Prokaryotic vs eukaryotic typical size

Prokaryotic - 1-5um in diameter. Eukaryotic - 10-100um in diameter

Plasma membrane

Selectively permeable, allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell.

General structure of a plasma membrane

double layer of phospholipids

Surface area to volume ratio

6:1

Most efficient ratio

SA:V

Too big of a cell (volume) produces ___

too much waste

The eukaryotic cell’s genetic instructions are housed in the ____ and carried out by the ____

nucleus, ribosomes

The nucleus includes

Chromosomes, chromatin, nucleolus, ribosomes

Chromosomes

DNA is organized into discrete units called chromosomes.

DNA and proteins of chromosomes are together called ___

chromatin

Chromatin

condenses to form discrete chromosomes as a cell prepares to divide

Nucleolus

located within the nucleus, site of ribosomal RNA synthesis

Ribosomes

uses information from the DNA to make proteins

ribosome contents

ribosomal RNA and protein

What two locations do ribosomes carry out protein synthesis

On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes), manufacture proteins destined for insertion into membranes, packaging by golgi, or export.

Cytosol (free ribosomes), manufacture ____ that function in the ___

cytosol

nucleus contains most of the _____ and the most conspicuous _____

cells genes, organelle

Nuclear envelope

encloses the nucleus, separating it from the cytoplasm

The nuclear membrane is a _______, each membrane consists of a _______

double membrane, lipid bilayer

_____ regulate the entry and exit of molecules from the nucleus

Pores

The shape of the nucleus is maintained by the _____, composed of _____

nuclear lamina, protein

The endomembrane system regulates ____ and performs _____ in the cell

protein traffic, metabolic functions

components of the endomembrane system

nuclear envelope, ER, golgi apparatus, lysosomes, vacuoles, plasma membrane.

what are the components of the endomembrane system connected via transfer by

vesicles

can components of the endomembrane system be continuous

yes

Endoplasmic reticulum

Biosynthetic factory, continuous with the nuclear envelope.

Two areas in the endoplasmic reticulum

smooth and rough er

Smooth er characteristics

synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions. lacks ribosomes

Rough er characteristics

surface is studded with ribosomes, has bound ribosomes which secrete glycopropteins, distributes transport vesicles, proteins surrounded by membranes, is a membrane factory for the cell.

Golgi apparatus

shipping and receiving center, consists of flattened membranous sacs called cisternae. sorts and packages materials into transport vesicles.

lysosomes

digestive compartments, membranous sacs of hydrolytic enzymes that can digest macromolecules.

lysomal enzymes work best in ___ environment ______

acidic, inside lysosome

what do enzymes hydrolize

proteins, fats, polysaccharides, and nucleic acids

Vacuoles

diverse compartments, derived from er and golgi

autophagy definition

recycling the cells own organelles and macromolecules with enzymes

food vacuole

formed by phagocytosis, a lysosome fuses with the food vacuole and digests the molecules

contractile vacuole

found in freshwater protists, pump excess water out of cells

central vacuole

found in many mature plant cells, hold organic compounds and water

mitochondria definition

site of cellular respiration (use oxygen to generate ATP)

mitochondria characteristics

in nearly all eukaryotic cells, highly folded inner membrane called cristae, the inner membrane creates two compartments, intermembrane space and mitochondrial matri

what does the mitochondrial matrix do

catalyzes some metabolic steps of cellular respiration

cristae present a ______ for enzymes that synthesize ___

large surface area, atp

Chloroplasts definition

sites of photosynthesis (found in plants and algae)

Chloroplasts characteristics

contains the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis

where are chloroplasts found

leaves and other green organs of plants and in algae

chloroplast structure

thylakoids, membranous sacs, stacked to form granum. Stroma, the internal fluid

The chloroplast is one of a group of plant organelles called ___

plastids

Peroxisomes

bound by a single membrane, produce hydrogen peroxide and convert it to water, oxidation, relationship to other organelles unknown

The cytoskeleton is a network of fibers that _________

organizes structures and activities in the cell

cytoskeleton characteristics

interacts with motor proteins to produce motility. inside the cell, vesicles travel along “monorails” provided by the cytoskeleton

microtubules length

Hollow rods about 25nm in diameter 200nm to 25 microns long.

microtubules function

shaping the cell, guiding movement of organelles, separating chromosomes during cell division

centrosomes

microtubule organizing center

centrioles

nine triplets of microtubules arranged in a ring

cilia and flagella

locomotor appendages of some cells. Differ in their beating patterns

How does dynein “walking” move flagella and cilia

Dynein arms alternately grab, move, and release the outer microtubules. Protein cross-links limit sliding. Forces exerted by dynein arms cause doublets to curve, bending hte cilium or flagellum.

Microfilaments thickness and length

Thinnest components, solid rods about 7nm in diameter, built as a twisted double chain of actin subunits

microfilaments function

cellular motility. Contains myosin and actin. In muscle cells, thousands of actin filaments are arranged parallel to one another. Thicker filaments composed of myosin interdigitate with the thinner actin fibers

Intermediate filaments function

support cell shape and fix organelles in place. Intermediate filaments are more permanent cytoskeleton fixtures than the other two classes.

intermediate filaments length and diameter

range in diameter from 8-12 nanometers, larger than microfilaments but smaller than microtubules

Extracellular components and connections between cells help ________

coordinate cellular activities

cell walls of plant cells

Protects the plant cell, maintains its shape, and prevents excess uptake of water. 

what are plant cell walls made of

cellulose fibers embedded in other polysaccharides and protein

extracellular matrixes are made of

collagen, proteoglycans, fibro

extracellular matrix function

support, adhesion, movement, regul

animal cells lack cell walls but have ______

extracellular matrixes (ECM)

ECM proteins function

bind to receptor proteins in the plasma membrane called integrins

Intracellular junction 4 functions

support, adhesion, movement, regulation

Intracellular junction support function

channels that perforate plant cell walls, allow water and small solutes to pass from cell to cell

intracellular junction adhesion function

membranes of neighboring cells press together, prevents leakage of extracellular fluid

intercellular junction movement function

anchoring junctions, fasten cells together into strong sheets

intercellular junction regulation function

communicating junctions, provide cytoplasmic channels between adjacent cells

Cell junctions

neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact facilitated by interce

types of intercellular junctions

plasmodesmata, tight junctions, desmosomes, gap junctions

Plasmodesmata

channels that perforate plant cell walls. With this, water and small solutes can pass from cell to cell

Tight junctions

press neighboring cells together, preventing leakage of extracellular fluid

Desmosomes

fasten cells together into strong sheets

Gap junctions (communicating junctions)

provide cytoplasmic channels between adjacent cells