Cell Structure & FunctionChapters 6, 7 & 12

Hershey High School BiologyMr. Barber

Types of Cells

P la n t C e lls A n im a l C e lls

E u ka ryo tic C e lls P ro ka ryo tic C e lls

C e ll T yp e s

http://www-class.unl.edu/bios201a/spring97/group6

Animal Cells

The Cell Nucleus

Why have nuclear pores at all?

What materials can pass through the nuclear envelope? What materials are retained?

What is in the nucleolus?

What molecules are in chromatin?

Plasma Membrane Structure

Understand the structures and properties of the plasma membrane.

Chapter 7

Endoplasmic Reticulum

What are the two types of ER?

How does the role of each type differ?

What kind of cells would have a lot of rough ER? Smooth ER?

Golgi Apparatus

Courtesy of Camillo Golgi, Italian cytologist, 1890.

What is the function of Golgi?

Each flattened sac is a __________.

How is the Golgi apparatus oriented within the cell?

Lysosomes How many membranes?

Where are lysosomes formed?

Contain what? Describe the internal

environment of a lysosome.

List three major functions.

What is the relationship between Tay Sachs disease and lysosomes?

Mitochondrion How many membranes? Why?

What cells would have high numbers of mitochondria?

What do mito. have to do with cloning?

What is the current theory on mito. origin?

Ribosomes Non-membrane bound! Composed of ______ and

________. Sites to synthesize

__________. How are prokaryotic

ribosomes different from eukaryotic ribosomes?

Antibiotics, including tetracycline and streptomycin, paralyze prokaryotic ribosomes. Why don’t these drugs harm eukaryotic ribosomes?

Centrioles Only in animal cells. Microtubule-producing

center. How are they usually

arranged within the cell? During cell division,

centrioles organize the spindle. What is the spindle?

If plants cells lack centrioles, do they form a spindle?

Cytoskeleton Enables a cell to change shape Anchors organelles and cytoplasmic enzymes Basically just non-membrane bound organelles

that can self-assemble. If the cytoskeleton organelles do not require the

nuclear input, then from where are these structures inherited?

Cytoskeleton contains: Microtubules Microfilaments (actin fibrils) Intermediate fibrils

Microtubules Hollow tubes of globular proteins called tubulins.

Extend outward from organizing center, _________.

Can be broken down, and rebuilt elsewhere. Come up with a good analogy for microtubules.

List three functions of microtubules.

Microfilaments Solid rods of the

protein actin. Where else do we find a lot of actin?

What are the functions of microfilaments?

Cilia and Flagella Structure of

cilia and flagella is the same. What separates these terms?

Note the basal body in the lower left. What is a basal body?

Cooked Meat What type

of tissue is this.

What is different about the cell membranes in this picture?

Can you spot the nuclei?

Mouse Intestines The thick, dark areas

in the bottom of the picture do not represent thickened cell membranes or cell walls (obviously).

What is this space called?

Why is it important to intestine cells?

Frog Blood What are the

cells shown in this picture?

What organelles can you see? Are you sure?

Plant cells

Plant Cell Organelles The following organelles are shared by both plant

cells and animal cells: Mitochondria Golgi ER (both types) Nucleus (and nucleolus) Plasma membranes Peroxisomes Ribosomes

The organelles specific to plants cells are described in the following slides.

Vacuole What

materials can be found in the plant vacuole?

Contractile vacuoles are found in Protists.

Plant Cell Wall Comprised of

___________. What are the

properties of the plant cell wall?

What would the role of the cell wall be during times of drought or excessive rainfall?

Tree trunk vs. sapling?

Plasmodesmata

What are the functions of plasmodesmata?

What kind of molecules can pass and what molecules are restricted?

Plastids Became integrated in the same manner as

mitochondria – some eukaryotic cells acquired bacteria.

Added photosynthetic powers to cells. Three types of plastids:

Amyloplasts white in color, stores starch, found in roots & tubers (i.e. potatoes)

Chromoplasts many colors, important in Ps Chloroplasts this is one will will investigate

(see next slide)

Chloroplasts How many

membranes? What color?

Why? Found in leaves

and stems. Be sure to

understand the internal structure of a chloroplast.

Potato Cells

What are the circles inside the cells?

Onion Cells

Note the heavily stained circle in the center. What are they?

Tracheids – Woody Stem Note the

rows of box-like cells.

What are tracheids?

Why is the bottom half stained differently than the top half?

Diatom What is a

diatom? What elements

are you most likely viewing?

This image is contrasted with darkfield microscopy.

Prokaryotic Cell

Prokaryote Characteristics Four main shapes

Bacillus (pl. bacilli): rod shaped More surface area than cocci Why would this be important to a free-living

organism?

Coccus (pl. cocci): sphere shaped Less distortion

Spirillium: spiral shaped Spirochetes: Spiral shaped with flagella

Very Motile

Prokaryote Characteristics (cont.) DNA Loop

Naked loop (not associated w/ proteins) Mainly housed in nucleoid region

Plasmids Small, circular loops of extrachromosomal

DNA Ribosomes

Free floating

Prokaryote Characteristics (cont.) Cell wall Why does a cell wall benefit a free-living organism? Gram Positive: Thick PG layer w/ no outer layer Gram Negative: Multi-layered & complex cell wall.

Thin PG layer surrounded by a lipopolysaccharide membrane.

**Penicillin inhibits the development of peptidoglycan. Which bacterial type is more affected by penicillin?

** Tears, mucous, and saliva contain ______ that dissolve bacterial cell walls away.

Prokaryote Characteristics (cont.)

Capsule: Some bacteria develop a jelly-like coating surrounding the cell wall.

Four functions: Prevents the cell from drying out Helps the cells to stick to surfaces Helps prokaryotes to slide on surfaces Keep bacteria form being destroyed by host

organism

Prokaryote Characteristics (cont.) Flagella

Used for motility Spin like propellers Structurally different than eukaryotic flagella What is the difference?

Pili Short, bristle appendages with two functions

Attach bacteria to surfaces Assist in transfer of DNA during conjugation

Paramecium

This is a single-celled protist.

What organelles can you identify?

Plasma Membrane: Fluid Mosaic Model 1 2 3 4 5 6 7 8 9

Fluidity Membrane must be fluid to work properly Cholesterol (in eukaryotic membranes)

controls the fluidity in two ways: In warmer temperatures, it decreases fluidity

by restraining phospholipid movement In colder temperatures it increases fluidity by

preventing the close packing of phospholipids

Mosaic A mosaic of proteins is imbedded and dispersed in

the phospholipid bylayer. Two protein types (depending on their location)1) Integral Proteins: Inserted so the hydrophobic

region of the protein is surrounded by the hydrocarbon portion of the phospholipid Unilateral: reach only partway across the membrane Transmembrane: completely span the membrane

(Chemically, how do you think these proteins are arranged?)

2) Peripheral Proteins: Not imbedded, but attached to the surface May be attached to integral proteins May be held by filaments

Movement of Substances Cell membrane must act as a selectively permeable

barrier This prevents passive movement of most molecules

There are seven ways a substance can get into a cell: Bulk Flow Diffusion Osmosis Facilitated Diffusion Active Transport Vesicle-Mediated Transport Cell-Cell Junctionhttp://www.biointeractive.org

Bulk Flow

Molecules move all together in the same direction

Hydrostatic pressure forces molecules through the plasma membrane

Where in our bodies can you find high hydrostatic pressure acting on molecules?

Note the hydrostatic pressure acting on the basement wall.

Diffusion Movement

of molecules from high to low concentra-tion

Requires no energy

Only very small molecules can diffuse through the membrane.Which ones?

Diffusion Rates…..Determined by Several Factors Distance

The ________ the distance the _______ the rate of diffusion. Gradient Size

The ___________ the concentration gradient the __________ the rate of diffusion.

Molecule Size The _________ the ion or molecule the _________ the rate of

diffusion. Temperature

The __________ the temperature the ________ the rate of diffusion. Electrical Forces

Electrochemical _______ exists whereby ___ are attracted by an opposite charge and the rate of diffusion is _________.

Osmosis Movement of

water through a semipermiable membrane from an area of high water potential to an area of low water potential until equilibrium is reached.

Does not require energy

Osmotic Environments Isotonic Environment Aqueous environment

has same solute concentration as cell. Water flows in & out equally.

Hypertonic Environment area outside cell has higher solute concentration. Water moves out of the cell. When the cell collapses and dies, this is known as _____.

Hypotonic Environment environment has lower solute than the cell. Water moves into cell.When a cell bursts, this in known as cell _________. What happens in plant cells?

Facilitated Diffusion

Since lipid layer is amphipathic, most polar molecules cannot pass through the nonpolar region.

Most organic molecules are polar

Ex: Glucose & amino acids enter a cell via facilitated diffusion, rather than simple diffusion.

Does not require energy Transport into cell

depends upon integral membrane proteins

These proteins are highly selective – called permeases.

Types of Transport Proteins Uniport carries a single molecule across a

membrane Ex: Glucose enters a cell

Symport moves two different molecules at the same time in the same direction. Both must bind to protein Ex: Na+ and Glucose enter a cell

Antiport two molecules move in opposite directions Ex: Na+ and K+ move through a membrane

These proteins can be inhibited by molecules that mimic the normally transported molecules.

Active Transport

Requires energy & membrane proteins Substance moved AGAINST its concentration gradient

Vesicle Mediated Transport

Vesicles or vacuoles can fuse with the cell membrane

Exocytosis

Exocytosis: Vesicles form inside the cell, move outward, fuse with the cell membrane, and expel their contents.

Endocytosis: Three Types Phagocytosis (cell eating): a solid substance

brought into the cell What organelle will fuse with the vesicle once

inside the cell? Pinocytosis (cell drinking): substance is a

fluid Receptor-Mediated: molecule attaches to a

specific receptor on the cell surface before a vesicle forms around the molecule

Receptor-Mediated Endocytosis

Note the receptors and path of the LDL Correlate this slide with Figure 5.22 in your book.

Cell-Cell Junctions Note the gap

junctions in the lower right. What purposes

do these junctions serve?

Note the tight junction in the upper left. What purposes

do tight junctions serve?

Plasmodesmata are found where?

The Cell Cycle Review of terms Humans have ____ chromosomes in each somatic

( ) cell. Each cell inherits a copy of the ___ chrom. What happens to the organelles? The following terms must be understood in order

to investigate mitosis. Genome: Chromosome: Chromatid: Centromere (kinectochore):

Stages of the Cell Cycle Typically the cell

cycle has 4 stages: G1 phase, S phase, G2

phase, & M phase Which letters

represent Interphase? The cell cycle is an

endless repetition of mitosis, cytokinesis, growth and chromosomal replication. Some cells break out of their cycle to die. (fingernail cells)

G1 Phase Physiologically

active time for cell

Chromosomes decondense

DNA consists of a single unreplicated helix

Cells perform many intense biochemical activities.

S Phase

DNA & chromosomal proteins are replicated

Lasts a few hours

G2 Phase Between

Synthesis & Mitotic phases

Mitotic Spindle proteins are synthesized.

What is the spindle?

M Phase: Mitosis & Cytokinesis

IPPMAT describes the cell cycle

How many stages of mitosis can you identify?

Prophase Chromosomes

condense. Be able to

describe condensed chromosome structure.

Nucleoli disappear

Prometaphase (Late Prophase)

Nuclear envelope fragments

Microtubules of the spindle can now interact w/ chromosomes.

What is the role of the centriole?

Metaphase Chromosomes line up on metaphase plate

Centromere line sup on the meta. plate – the chromatids on the chromosomes can be pointed in any direction.

Anaphase Sister chromatids separate and move to opposite ends of the cell

Early anaphase (top)

Late anaphase (bottom)

Telophase Reverse of prophase Now there are two

nuclei instead of one. Chromosomes

decondense Nuclear membrane

reappears Spindle fibers

become disorganized Cell pinches in the

middle

Cytokinesis End result is two

daughter cells In animal cells

there is a cleavage furrow

In plant cells there is a cell plate

Which one is shown in the picture to the left?