• The cell is the lowest level of structure that is capable of performing all the activities of life.

• The first cells- cork, Robert ___________ in 1665.

• Anton van ________________ - first saw single-celled organisms in pond water and observed cells in blood and sperm.• In 1839, Matthais Schleiden and Theodor

Schwann – The ________________- all living things

consist of cells.• A cell theory extension - all ______ come from other

_____.

Cell Structure and FunctionChapter 4

Early Discoveries

• Smallest unit of ____

• Can survive _____________ or has

potential to do so

• Is highly organized for __________

• Senses and responds to ____________

• Has potential to ________________

Cell

• Prokaryotic vs eukaryotic cells

•Similarities-

•A ___________________.

•A ______ (semifluid substance) within the cell

•_______________

•__________- organelles that make proteins

•Differences

•Euks have chromosomes in a ____________(compared to a nucleosome in proks.)

•Euks have many _______ __________________

•Eukaryotic cells are __________times larger

• Larger organisms do not generally have _______cells than smaller organisms - simply _______cells.

Structure of Cells

• Main component of cell ____________

• Gives the membrane its _____ properties

• Two layers of ______________

Lipid Bilayer

Fluid Mosaic Model• Membrane is a mosaic of

– _______________– ______________– Sterols– _______________

Membrane Proteins• __________proteins

• _________ proteins

• Recognition proteins

• ___________ proteins

Why Are Cells So Small?• Surface-to-volume ratio

• A bigger cell = less _________________ per unit volume

• Above a certain size, material cannot be moved in or out of cell _____________

0.5 1.0 1.5

0.79

0.06

3.14 7.07

0.52 1.77

Diameter (cm):

Surface area (cm2):

Volume (cm3):

Surface- to-volume ratio: 13.17:1 6.04:1 3.99:1

Fig. 4.5, p. 54

• ___________ microscope -minimum resolution is - _ _______ ( the size of a small bacterium)

For higher resolution--__________ microscope-Transmission Electron Microscope-Scanning Electron Microscope

Microscopy

Fig. 7.7

Animal cell

Animal cells lack:•_____________•_____________•______________•______________

Fig. 7.8

Plant cell

Plant cells lack:•__________•___________•__________

Most other components are __________by plant and animal cells

• contains most of the _____ in a eukaryotic cell.

– Some genes are in ___________ and _____________

• separated from the cytoplasm by a ____________ membrane.

• Protein pores allow large macromolecules and particles to pass through.

• ______________ (located internal to the membrane)- maintains nuclear __________

1. The nucleus

• ___________ (DNA and associated proteins) – Each eukaryotic species has a

characteristic number of _________________.

– A typical human cell has 46 chromosomes, but sex cells (eggs and sperm) have only 23 chromosomes.

• ___________- densely stained fibers and granules adjoining chromatin

•Factory for ribosomal RNA (rRNA)

•rRNA is a component of ______________

_____________-

• contain _______ (from nucleolus) and __________.

• composed of two subunits

• carry out __________ synthesis.

2. Ribosomes build a cell’s proteins

Fig. 7.10

• Found in _______locations-– 1. “_____” ribosomes -suspended in the

cytosol – Function: synthesize ______________ proteins

– 2.”_____” ribosomes- attached to the outside of the __________________________• Function: synthesize __________ proteins

and ____________ proteins– Note: Ribosomes can shift locations.

Ribosomes- (cont.)

• The _____________________- includes

• the nuclear envelope

• endoplasmic reticulum

• Golgi apparatus

• lysosomes

• vacuoles

• plasma membrane.

• Where are the membranes produced?? The _____

• Two regions of ER that differ in structure and function.

– _______ ER

• ribosomes attached to the outside

• Packages proteins into ____________________

– __________ ER

• lacks _____________• Function: synthesize lipids,

including oils, phospholipids, and steroids– Also _________________

drugs and poisonsFig. 7.11

3.The endoplasmic reticulum

• Function: _________, ____, and ______ cell products

• Many transport vesicles from the ER travel to the ________ __________________ for modification of their contents.

4. The Golgi apparatus

Cis face“receiving”

Trans face“shipping”

____ face _______ vesicles from ER; ______ face ships vesicles out

• a membrane-bounded sac of ________ enzymes

• functions -digest ________________ (proteins, fats, polysaccharides, and nucleic acids).

• Low pH (5.0)

5. Lysosomes

Fig. 7.13a

•massive leakage from lysosomes can destroy an cell by __________

Nucleus

Lysosome

• The lysosomal enzymes and membrane are synthesized by ________ and then transferred to the ___________.

• At least some lysosomes bud from the trans face of the ______.

Fig. 7.14

5. Lysosomes (Cont.)

Inherited diseases affect _______________ metabolism:– These individuals lack a functioning version of

a normal hydrolytic enzyme.– Result- Lysosomes are engorged with

______________ substrates.• ____________ disease in the liver • Tay-Sachs disease in the brain.

• Lysosomes can fuse with __________________ or another organelle

5. Lysosomes (Cont.)

• Vesicles and vacuoles (larger versions) are membrane-bound_____ with varied functions.– ___ vacuoles, from

phagocytosis, fuse with lysosomes.

– _________vacuoles, found in freshwater protists, pump excess water out of the cell.

– __________ vacuoles are found in many mature ______cells.• Functions - stockpiling

proteins or inorganic ions….,

6. Vacuoles

• Convert energy to forms that cells can use for work.

• __________ -site of _______ _____________, generating ATP from the catabolism of sugars, fats, and other fuels in the presence of oxygen.

• ___________, found in plants and eukaryotic algae, are the site of ________________.– They convert solar energy

to chemical energy and synthesize new organic compounds from CO2 and H2O.

7. Mitochondria and chloroplasts

Chloroplast

Mitochondria

• Mitochondria and chloroplasts-– Are _____ part of the endomembrane system.

• Proteins from ____ ribosomes in the cytosol (and a few from their own ribosomes).

– Contain DNA– Grow and reproduce as ______________

organelles.

• Almost all ____________ cells have mitochondria.

• Cells may contain one to __________________.

• The number of mitochondria is correlated with aerobic metabolic activity.

• Endoplasmic reticulum

• Ribosomes

• Nucleus

Review

• Nucleolus

DNAProduce mRNA

Produce rRNA (for ribosomes)

Protein synthesis

Produce membranes

FUNCTION

Golgi

Function

Finishes, sorts, and ships _____________

LysosomeNucleus

digest -__________

Vacuole•Food vacuole•Central vacuole (plants)

•Transport food to lysosome•Give plants rigidity

Chloroplast

Mitochondria •Produce ATP for energy

•Capture light for energy (only chloroplasts)

• generate and degrade -_______________ (H2O2) in performing various metabolic functions – H2O2 is _______, but the peroxisome has

another enzyme that converts H2O2 to water.

8. -_______________

•Functions:

• break ___________ down for fuel.

•__________ alcohol (and other harmful compounds).

•Convert the fatty acids in seeds to sugars

•Not part of __________- system

• The ____________ is a network of _______ extending throughout the cytoplasm.

• ________: – Organizes the

structures and activities of the cell.

– provides __________ support and maintains shape of the cell.

– provides ____________ for many organelles and cytosolic enzymes

– dynamic

9. Cytoskeleton

Fig. 7.20

• There are three main types of fibers in the cytoskeleton:

• ______________

• ________________

• __________________.

9. Cytoskeleton (Cont.)

Fig. 7.21b

microfilaments

Intermediate filaments

(Keratin)

(Actin)

Function in plants: _____________, maintains its shape, and prevents excessive uptake of water.– It also supports the plant against the force of

____________.

10. Cell wall – Plant and proks, but not animal cells

• Composed of microfibrils of _______ embedded in a matrix of proteins and other polysaccharides.

•steel-reinforced concrete analogy

Plasma membrane

• Can influence the activity of genes in the nucleus via a combination of chemical and mechanical signaling pathways.

• This may coordinate all the cells within a tissue.

• Function- support, adhesion, movement, and regulation

• Animals cells have an elaborate ____.

• -_________ fibers embedded in a network of ________________

• The _______ connect the ECM to the _______________.

11. The extracellular matrix (ECM)

• Function- Cell to cell communication and cell-cell contact

• Plant cells are perforated with ______________, channels allowing cysotol to pass between cells.

12. ____________________

Fig. 7.28 inset

Animal Cell Junctions

tightjunctions

adheringjunction

gapjunction

Animal have 3 main types of intercellular links:

• __________________ and Eubacteria

• DNA is NOT enclosed in ____________

• Generally the smallest, ___________ cells

• No _______________

Prokaryotic Cells

Prokaryotic Structure

DNA

pilus

flagellum

cytoplasm with ribosomes

capsulecell wall

plasma membrane