Biology/Chapter 7 notes-CELL STRUCTURE & FUNCTION



Biology/Chapter 7 notes-CELL STRUCTURE & FUNCTION

I. Life is Cellular

A. 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_________________

1. All living things composed of ___________

2. Cells are the basic units of ___________________________of living things

3. New cell are produced from __________________________.

B. 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 _______________________.

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2. _____________________________-contain a nucleus w/ genetic material,generally larger,much diversity.

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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

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____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

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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?______________

2. Diffusion

o In a solution the particles move constantly,spreading out randomly….tending to move where more concentrated to an area less concentrated…This is called __________________.

o ________________________________= concentration of a solute is the same throughout a system

o does not require energy because random movement

o if equilibrium is reached,particles keep moving across the membrane,still balancing concentration

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D. Osmosis

o Some molecules are too large or too strongly charged to make it across the lipid bilayer----thus impermeable to it

o Most membranes are selectively permeable

o _____________________is the diffusion of water across a selectively permeable membrane

o 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

o ____________________-same strength of a solute on both sides of a solute

o more concentrated side of solute is ____________________

o less concentrated side is____________________________

o Osmosis exerts a pressure known as ______________________________________on the hypertonic side of a membrane….This could results in a cell bursting

o Bursting not so much a problem in larger organisms…-tend to be in isotonic environments

o Osmotic pressure may not allow a plant or bacterial cell to burst,but could weaken the cell wall

o

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See p.186

E. 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

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F. 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

2. 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

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IV.The diversity of cellular life

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

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