Chapter 6 A Tour of the Cell -...

Biology – Kevin Dees

Chapter 6A Tour of the Cell


• The cell is the ______ _____ of _____

• Although cells differ substantially from one another, they all share certain characteristics that reflect a common ancestry and remind us of the unifying theme of evolution

• Three main parts of a cell– Plasma membrane– Cytoplasm– Genetic control


History of the cell• First ‘microscopes’ – 1590 • ________ _______

– coined the term “cell” in 1665

• Little knowledge was gained about cell structure –function until the 1950’s– WHY??


Microscopes• Essential tool for studying the cell

– Light microscopes – Electron microscopes – much higher

magnification and resolution • Electron microscopes made the detailed

study of cell ultrastructure possible


Comparison of Light , Transmission electron and Scanning Electron microscopy


Recall, that there are two basic categories of cells:

• ___________ cells –– Without a true nucleus – organisms in the Domain Archaea and

Bacteria

• ____________ cells-– With a true membrane bound nucleus– plants, animals, fungi, etc..


Prokaryotic cells

• Very simple – contain:– Plasma membrane– Cytoplasm– Genetic control

• No nucleus –prokaryotic chromosome is not enclosed in a membrane!!!!!


Eukaryotic cells

• True nucleus – genetic material is surrounded by membrane.

• Typically larger than prokaryotic cells but still small


• Why are cells small?

• Large living things typically do not have larger cells? Why??


Plasma membrane

• Forms a selective barrier to allow the controlled passage of materials in and out of the cell

• General construction– ___________________ _________ and ___________

• Forms the surface area of a cell


Surface area regulates cell size• Materials must pass in-out of cell.• Must pass through plasma

membrane• Smaller objects tend to have a higher

ratio of surface area to volume


Comparison of typical animal and plant cells

• Recall the three components that all share have in common:1. _____________2. _____________3. _____________

• We are going to survey generalized animal and plant cells– Look for similarities and differences between

the two


General Animal cell

A

B

C

D

E

F

G

H

I

J

KL

M

N


General Plant cell

A

B

C

D

E F

G

H

IJ


• Nuclear envelope– Nuclear pores– Function- ________________________________________

• Nucleolus– Function- __________________________________________


Genetic material in nucleus• Genetic material- DNA and some proteins

– When cell is functioning normally, it is the form of ______________________________

– When cell is preparing to divide, it is in the form of ______________________________

– Somatic cells are ________________________________

– Gametes are ___________________________________

– Humans – 23 pair of chromosomes in somatic cells– 23 single chromosomes in gametes

• Why??????


Ribosomes

• Function of a ribosome ____________________________

• Structure of a ribosome– Not surrounded by a membrane– Made of RNA and Proteins– Large and small subunits

• Location– Bound ribosomes – attached to ________________________– Free ribosomes – found in ____________________________


Main parts• Nuclear envelope• Rough Endoplasmic

reticulum• Smooth endoplasmic

reticulum• Golgi complex• Vesicles

Endomembrane system


• __________________– Synthesis of lipids, steroids,

phospholipids– Detoxification

• ___________________– Important in protein synthesis– produces more ‘membrane’ for

the cell

• __________________– Products refined, stored,

sorted, shipped

• _________________– Used for transport

Endomembrane system


• The cis face is located ______________the ER– Transport vesicles from the ER move materials to the Golgi

• The trans face is located ______________ the ER – Gives rise to vesicles which move away from the Golgi

Golgi apparatus


• ________________ Membranous sacs of hydrolytic enzymes for intracellular digestion

• (a) ____________creation of food vacuole and subsequent digestion

• (b) ______________ recycles cellular components


• Vacuoles - function =______________________

– Food vacuoles

– __________ vacuole found only in plant cells

• _______________ membrane that surrounds central vacuole

• Turgor pressure – water– Storage of electrolytes


• Mitochondrion (sing) mitochondria (plural)

– Free ribosomes and mitochondrial DNA

– Site of _____________________________


• Chloroplasts – Found in ____________ cells

• Site of ____________________


__________________________Functions for support, motility and

regulation

• ___________– Pair of centrioles– Creation of the

mitotic spindle used during cellular division


• Cilia

• Flagella


Cell wall of plants• Composed of ____________• Structure for plant cell

• ____________________– Connections between plant

cells

• _________________– joins adjacent plant cells


Cellular junctions• Plant cells

– Plasmodesmata• Animal cells

– Tight junctions• Continuous seal

– Gap junctions• Communication

between cells– Desmosomes

• ‘rivets’


All activities of cells must be coordinated

• The ability of the macrophage to recognize the harmful bacteria, locate them, capture them, and engulf them to be destroyed takes a coordinated effort

Chapter 6 A Tour of the Cell -...

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