Biology/Chapter 7 notes-CELL STRUCTURE & FUNCTION

  1. Life is Cellular
  2. The Discovery of the Cell

It was not until the ______that scientists began to use microscopes to observe organisms.

In 1665 ______used an early compound microscope to see tiny chambers in cork.He called these chambers cells after the tiny rooms in monasteries….we know these not to be empty now.

About the same time in Holland______used a single-lens microscope to look @ pond water,

Cell Theory

  • In 1838 Mathew Schleiden concluded plants were made of cells
  • 1839 Theodore Schwann said all animals were made of cells
  • 1855-Virchow said cells could only come from existing ones.
  • These 3 things compile______
  • All living things composed of ______
  • Cells are the basic units of ______of living things
  • New cell are produced from ______.
  1. Exploring the Cell

Florescent labels and light microscopy have been used to follow molecules through the cell.

______,which scans cells w/a laser beam can make 3-d images of cells

Video technology make it possible to watch cell growth,division and development

Light makes it difficult to visualize tiny structures because it scatters/______allow things like proteins be visualized (things as much as 1000 x smaller can be visualized….TEMS allow you to see specimens cut into ultra thin slices

W/ a ______specimens do not have to be cut to see 3-D images….Both must be placed into a vacuum so air molecules do not scatter electrons

1990’s-______have revolutionized visualization of surfaces and atoms have been observed…can be used in ordinary air and can show DNA structure

C .Prokaryotes and Eukaryotes

Cells typically range from ______micro- meters,but some bacteria are .2 and some amoeba are 1000 micrometers

All cells have 2 things in common:

  1. cell membrane-a barrier
  2. @ some point they contain______

2 broad categories:

  1. ______-genetic material is NOT contained in a nucleus/generally less complicated than other cells/carry out all cell activities…present day members are ______.
  1. ______-contain a nucleus w/ genetic material,generally larger,much diversity.

Chapt, 7 II. EUKARYOTIC CELL STRUCTURE

•Organelles=Specialized structure that performs important functions within an eukaryotic cell.

•2 major parts of eukaryotic cells-nucleus & cytoplasm--Cytoplasm is material inside membrane and outside nucleus

____The Nucleus

•Contains nearly all the cell’s DNA

•Codes for instructions to make proteins and other molecules

•Surrounded by nuclear envelope---has many pores to allow material in and out

•Contains chromatin—has DNA bound to protein,usually spread throughout nucleus,but condenses during cell division to make CHROMOSOMES,containing genetic info

•Usually contain Nucleolus—assembly of ribosomes begin here.

____Ribosomes

•Proteins are assembled here

•Made out of small particles of RNA and protein

•Found throughout cytoplasm

•Coded instructions from nucleus tell how to make proteins

•Cells active in protein synthesis have a lot of ribosomes

---Endoplasmic Reticulum

•Site where lipid components of cell membrane are assembled,along w/ proteins and other materials exported from cell(those proteins are made there)

•Rough ER is involved in protein synthesis,because ribosomes are on it

•Newly made proteins leave ribosomes and insert on rough ER ,where they may be modified

•If cell makes a lot of protein ,there is much ER

•Smooth ER may contain many specialized enzymes

----Lysosomes

•Small organelles filled w/enzymes

•May digest or break down lipids,carbs,and proteins into small molecules that can be used by the rest of the cell

•Lysosomes remove “junk”,or used up organelles…-very important that this aspect / function occurs

--Vacuoles

•Sac like structures that store water ,salts ,proteins, and carbs

•Plants may have a single large water filled vacuole

•Contractile vacuoles control water in paramecium

==Mitochondria and Chloroplasts

•Most all eukaryotic cells contain mitochondria that convert chemical energy stored in food into compounds convenient for cell to use

•Mitochondria have an outer and inner membranes

•In humans,nearly all mitochondria comes from ovum(egg cell)

--

Chloroplasts

•Capture energy from sunlight and convert into chemical energy in photosynthesis

•Contain 2 membranes and chlorophyll

--Organelle DNA

•In chloroplasts and mitochondria

•Small DNA molecules

•Maybe descendants of early prokaryotes

•----Endosymbiotic theory says these prokaryoic ancestors developed a symbiotic relationship w/ early eukaryotes and resided within---evolving into mitochondria

==Cytoskeleton

•Network of protein filaments that help cell maintain shape

•Also involved in movement

•MICROFILAMENTS are threadlike structures made of a protein-actin….make a major network and a tough framework///allows amoebas and such to move

•MICROTUBULES-hallow structures made of proteins called tubulins—important in holding a cell’s shape----form a mitotic spindle in cell division/which helps separate chromosomes

•CENTRIOLES are microtubules near nucleus in animals and help organize cell division

•Microtubules also help make projections like cilia or flagella

Chapter 7 Notes cont’d

III. Cell Boundaries

All cells have a ______and some have a cell wall.

A.Cell Membrane

Regulates what enters and leaves the cell and also provides ______.

Almost all cell membranes are made of a double layered sheet called a ______-flexible,yet strong barrier

Cell membranes usually have a protein molecule imbedded in the bilayer w/ carbohydrate molecules attached

Called a ______model

Some of the proteins form channels or pumps to move material across the membranes

Some of the carbs act as ______tags

B. Cell Walls

In plants,algae,fungi, and many prokaryotes

Lie ______the cell membrane

Usually porous enough to let water,O2,CO2 and certain other substances to pass through easily

Main function is support and protection

Usually made of fibers of ______-produced in cell and secreted to surface

Mostly ______-tough carb fibers

C.Diffusion Through Cell Boundaries

Every cell is in a liquid environment

Cell membrane regulates the movement of cell materials from one side to the other

  1. Measuring concentration

Cytoplasm is a solution of various substances in water

______of a solution is the mass of solute in given volume of solution---ie. Mass/volume…..If you have 15 g salt in 3 L water,what is the concentration?------______….If you have 24 g salt in 2L water you would have 12 g/mL salt….Which solution is more concentrated?______

  1. Diffusion
  2. In a solution the particles move constantly,spreading out randomly….tending to move where more concentrated to an area less concentrated…This is called ______.
  3. ______= concentration of a solute is the same throughout a system
  4. does not require energy because random movement
  5. if equilibrium is reached,particles keep moving across the membrane,still balancing concentration

  1. Osmosis

  • Some molecules are too large or too strongly charged to make it across the lipid bilayer----thus impermeable to it
  • Most membranes are selectively permeable
  • ______is the diffusion of water across a selectively permeable membrane
  • water moves easily and will move to balance the concentration of a solute,water moving from area of higher to lesser conc…..ie For the WATER
  • ______-same strength of a solute on both sides of a solute
  • more concentrated side of solute is ______
  • less concentrated side is______
  • Osmosis exerts a pressure known as ______on the hypertonic side of a membrane….This could results in a cell bursting
  • Bursting not so much a problem in larger organisms…-tend to be in isotonic environments
  • Osmotic pressure may not allow a plant or bacterial cell to burst,but could weaken the cell wall

See p.186

  1. Facilitated Diffusion

Some molecules,like glucose ,diffuse quickly across due to ______

These allow only certain molecules to pass

Since it is diffusion it does not require energy and still goes from area of higher to lower concentration

  1. Active Transport---Movement ______

Requires much energy

Usually carried out by proteins or pumps found in the membrane

  1. Molecular Transport

Small molecules and ions carried by proteins that act like energy requiring pumps

Ca ,K,and Na ions are carried

  1. Endocytosis and Exocytosis

Transports larger molecules and even clumps of matter

______is the process of taking material inward by enfolding,or pockets

In endocytosis ,the pocket breaks loose from the cell membrane and forms a vacuole…large molecules,food and even whole cells can be taken in this way

2 examples of endocytosis are

  1. ______-extensions of cytoplasm surround a particle and package it in a food vacuole,then the cell engulfs it ---This is how amoebas eat-----is a form of active transport
  2. ______-Cells use this to take up liquids in the environment—tiny pockets filled w/ liquid form along the cell membrane and pinch off to form vacuoles
  3. ______--releases large amounts from the cell by pinching off or a contractile vacuole as in paramecium---also active transport

IV.The diversity of cellular life

Take your own notes here,using book and/or powerpoint

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