Cell Notes 

 

Parts of the Cell Theory

1.     Cells are the basic unit of structure and function in an organism.

2.     All living things (organisms) are composed of cells.

3.     Cells come only from other living cells.

 

Contributors to the Cell Theory

1.     Matthias Schleiden –  said all plants are composed of cells

2.     Theodore Schwann â€“ said all animals are composed of cells

3.     Rudolf Virchow â€“ said cells only come from other living cells.

 

Two Types of Cells

1.  Prokaryotes do not contain a nucleus

2.  Eukaryotes do contain a nucleus

*Compare and contrast prokaryotes and eukaryotes*

 

Compare:

1.     Both are cells.

2.     Both carry out all the life processes.

A.   Respiration

B.    Homeostasis

C.   Reproduction

D.   Response

E.    Growth

F.    Metabolism

3.     Both contain DNA

 

 

 

Contrast:

1.     Prokaryotes lack a nucleus

2.     Eukaryotes contain a nucleus

3.     Prokaryotes lack organelles

4.     Eukaryotes contain organelles

5.     Prokaryotes are various types of bacteria

6.     Eukaryotes are protists, fungi, plants, and animals

7.     Prokaryotes include the Domains Bacteria and Archaea

8.     Eukaryotes include the Domain Eukarya

9.     Prokaryotes include the Kingdoms Eubacteria and Archaebacteria

10. Eukaryotes include the Kingdoms Protista, Fungi, Plantae, Animalia

 

*Describe the role of sub-cellular structures in the life of a cell*

Organelles  – (little organ) tiny structure that performs a specialized function in the cell.

Organelles:

1.     Nucleus controls the cell, contains DNA and is the information center of the cell.  

    Three forms of DNA in the nucleus

A. Chromatin which are thin threads.

                   B.Chromatids which are single strands.

                   C.Chromosomes which are double strands. 

     The nucleus is surrounded by the nuclear envelope which is

     composed of two membranes with

     nuclear pores that allow molecules to

     move into and out of the nucleus

2.     Nucleolus found in the nucleus.  It is composed of RNA and protein.  It is where ribosomes are made.

3.     Mitochondrion the powerhouse of the cell, the site of respiration.  Respiration is the process that releases energy from food.  All organisms must carryout respiration.  The mitochondrion contains membrane folds called cristae that increase surface area to increase respiration

4.     Ribsomes are the site of protein synthesis. 

     Two types of ribosomes

A.     Free ribosomes which occur in the cytoplasm and produce proteins used inside the cell.

B.      Ribosomes found on the endoplasmic reticulum  which make proteins that are transported out of the cell to be used elsewhere.

5.     Endoplasmic reticulum transports materials throughout the cell.  The site of lipid assembly to form the cell membrane.

    Two types of endoplasmic reticulum. 

A.Rough ER which contains ribosomes and transports proteins out of the cell.

B. Smooth ER which does not contain ribosomes and stores enzymes  especially those necessary to synthesize membrane lipids and detoxify substances.

    6.  Golgi apparatus modifies, stores,

         and packages materials to be used in the cell or

         transported out of the cell.

    7. Lysosomes store enzymes necessary for

   digesting certain materials in the cell.  Because they can destroy the cell

   they are called suicide sacs.

   They absorb the tail of a young frog and formed

    your fingers and toes.

8.     Vacuoles are storage organelles.

Contractile vacuoles pump out excess water

9.     The  cytoskeleton forms the framework of the cell.

 

 

 

Two Parts of the Cytoskeleton

A.     Microtubules -- hollow tubes of protein They provide support, allow for movement within the cell, and play a role in mitosis.  They also help to form cilia which are numerous hair-like projections that aid in movement and flagella which are whip-like structures that are usually few in number and aid in movement.

B.      Microfilaments are long, thin, fibers that allow for cytoplasmic streaming, which is the movement of cytoplasm within the cell.

10. Centrioles are found only in animal cells and are composed of microtubules and form the spindle during cell division.

11. Plastids are found only in plant cells.

 Three types of Plastids

A.     Chloroplasts are the site of photosynthesis

B.      Leukoplasts store starch

C.     Chromoplasts store the pigments xanthophylls (yellow) and carotenes(orange).

 

*Relate the function of the plasma (cell) membrane to its structure:*

The plasma membrane consists of two layers of phospholipids with embedded proteins.  This structure allows the membrane to maintain the shape and integrity of the cell and easily transport materials into and out of the cell.  The phospholipids are insoluble in water which keeps the cell together since most of the cell is water.  Even though the phospholipids do not dissolve in water many substances easily diffuse through the cell membrane.  The proteins act as carrier molecules and gated  channels to facilitate diffusion.  The membrane also plays a role in endocytosis and exocytosis.  The structure of the cell membrane enables cellular transport, both passive and active.  The structure of the cell membrane also holds the cell together.

*Compare and contrast the structures of an animal cell to a plant cell.*

Contrast:

1.     Plants have a cell wall for support; animals use water, endoskeletons, and exoskeletons

2.     Plants have chloroplasts to carry out photosynthesis;  animals cannot make their own food and must rely on plants for food

3.     Plants have a large central vacuole that provides support by filling with water and creating turgor pressure; animals have many small vacuoles

4.     Plant cells are usually more rectangular; animal cells are usually more round.

Compare:

1.     Both have a cell membrane to hold the cell together

2.     Both have mitochondria because they both need to release energy by respiration

3.     Both have a Golgi apparatus to package materials to leave the cell.

4.     Both have ribosomes to make proteins.

5.     Both have a nucleus to direct cell activities.  Both have DNA.  Both have a nucleolus to store RNA and make ribosomes

6.     Both have an endoplasmic reticulum to transport materials throughout the cell.

 

 

*Compare and contrast the functions of autotrophs and heterotrophs.*

 

Compare:

1.     Both require energy.

2.     Both carry out respiration to release energy from food.

 

Contrast:

1.     Autotrophs are able to use energy from the sun or chemicals to make their own food

2.     Heterotrophs must get their energy by eating other organisms.

Autotrophs supply energy for heterotrophs.

 

*Relate the development of the cell theory to current trends in cellular biology.*

 

The Janssen brothers developed a microscope in 1590.  Robert Hooke viewed cork through a microscope in 1665 and coined the term cell.  In 1674, Anton van Leeuwenhoek improved the microscope and observed organisms in pond water.  In 1831, Robert Brown discovered the nucleus.  In the mid 1800s, from the work of Matthias Schleiden, Theodore Schwann, and Rudolf Virchow the cell theory was developed laying the foundation for understanding all the structures and functions of every living thing.  Today, scientists working on cancer research studying the mechanisms and organelles of cells such as centrioles because centriole and cilia biogenesis are two processes that malfunction in certain cancers and kidney disease, would have not known where to begin to understand why some people got sick and died without the  cell theory. The realization that the cell is the basic unit of  structure and function gives scientists a starting point to understand the mechanisms of  disease.  Cells coming only from other cells supplies biologists with the foundation of how to clone body parts or better understand how abnormal cells are produced. This information is invaluable in the work on cancer treatment and prevention and the prevention of other

diseases.   

 

*Construct a hierarchy of life from cells to ecosystems:*

 

1.     cell – basic unit of structure and function in an organism.

2.     tissue  –  group of cells working together

3.     organ – group of tissues working together.

4.     system – group of organs working together

5.     organism –  a living thing

6.     population –  a local group of organisms belonging to the same species and capable of breeding

7.     community –  all the populations in one area

8.     ecosystem  –  the organisms in a plant population and the abiotic and biotic factors which impact them. 

     abiotic –  nonliving

biotic â€“  living

All the communities plus the abiotic factors