CELLS: ANIMAL CELLS 13 FEBRUARY 2013

Lesson Description

In this lesson we will discuss the following:

The Cell Theory

Terminology

Parts of a Microscope

The definition of a Cell

Examples of Cells

Type of Cells

Plant and Animal Cells

Parts of Animal Cells: Organelles

Key Concepts

The Cell Theory All living things are made up of cells and are either unicellular or multicellular.

Cells are the smallest working units of all living things that show the characteristics and

properties of life.

All cells come from preexisting cells through cell division.

How do living organisms compare in size:

Diagram adapted from Via Afrika Life Sciences Grade 10 Learners Book

Important Terms:

Cell Golgi body Phagocytic Cell membrane Mitochondrion Pseudopodia Centriole Nucleus Ribosomes Centrosome Nucleolus Vacuole Chromatin network Nuclear membrane Cytoplasm Organelle Endoplasmic reticulum

Parts of a Microscope:

Diagram adapted from Via Afrika Life Sciences Grade 10 Learners Book

Examples of Cells

Diagram of a Red blood cell Diagram of a Nerve cell

Diagram of a Bacterial cell Diagram of an Amoeba cell

Type of Cells

Prokaryotic

Eukaryotic

Prokaryotic Cells

Diagram of a Bacterial Cell

Characteristics of Prokaryotic cells

No true nucleus ,have stands of DNA or RNA

Do not have structures surrounded by membranes

Few internal structures

One-celled organisms, e.g. Bacteria

Eukaryotic Cells

Diagram of a Plant Cell

Characteristics of Eukaryotic cells

Have a true membrane bound nucleus

Have structures surrounded by membranes

Complex internal structures

Typical Animal and Plant Cells

Diagram showing the cross section of a typical animal cell

Diagram showing the cross section of a typical plant cell

Parts of Animal Cells A typical animal cell consists of the following parts:

A Cell membrane

A Nucleus

The Cytoplasm

The various organelles

Cell Membrane Outer membrane of cell that controls movement in and out of the cell

Double layer

Diagram showing the structure of a cell membrane

The fluid mosaic model describes the structure of the plasma membrane.

Different kinds of cell membrane models have been proposed, and one of the most useful is

the Fluid-mosaic model. In this model the membrane is seen as a bilayer of phospholipids

in which protein molecules are embedded.

Channels/pores - A channel in the cell's plasma membrane. This channel is made up of

certain proteins whose function is to control the movement of food and water into the cell.

These channels are made up of certain proteins.

Nucleus

Diagram showing the structure on a nucleus

The nucleus is the control center of the cell. It is the largest organelle in the cell and it

contains the DNA of the cell. The DNA of all cells is made up of chromosomes.

DNA (Deoxyribonucleic Acid) contains all the information for cells to live, perform their

functions and reproduce.

Inside the nucleus is another organelle called the nucleolus. The nucleolus is responsible for

making ribosomes.

The circles on the surface of the nucleus are the nuclear pores. These are where ribosomes

and other materials move in and out of the cell.

The Cytoplasm

Diagram showing the internal contents of Cytoplasm

Cytoplasm refers to the jelly-like material with organelles in it.

If the organelles were removed, the soluble part that would be left is called the cytosol.

It consists mainly of water with dissolved substances such as amino acids, vitamins and

nutrients in it.

Cellular Organelles

Mitochondrion

Diagram showing the electron micrograph of a mitochondrion

Mitochondria are membrane-enclosed organelles distributed throughout the cytosol of most

eukaryotic cells.

Their main function is cellular respiration in which y convert the potential energy of food

molecules into ATP.

Every type of cell has a different amount of mitochondria. There are more mitochondria in

cells that have to perform lots of work, for example- your leg muscle cells, heart muscle cells

etc. Other cells need less energy to do their work and have less mitochondria.

Diagram showing the internal structure on a mitochondrion

Structure of Mitochondrion

Mitochondria have:

an outer membrane that encloses the entire structure

an inner membrane that encloses a fluid-filled matrix

between the two is the intermembrane space the inner membrane is elaborately folded with

shelf like cristae projecting into the matrix.

Ribosomes

Diagram showing the structure of a ribosome

Ribososmes are organelles that help in the synthesis of proteins.

Ribosomes are made up of two parts, called subunits.

They get their names from their size. One unit is larger than the other so they are called large

and small subunits.

Both these subunits are necessary for protein synthesis in the cell. When the two units are

docked together with a special information unit called messenger RNA, they make proteins.

Some ribosomes are found in the cytoplasm, but most are attached to the endoplasmic

reticulum. While attached to the ER, ribosomes make proteins that the cell needs and also

ones to be exported from the cell for work elsewhere in the body.

Endoplasmic Reticulum

Diagram showing the structure of the endoplasmic reticulum

It is a network of membranes throughout the cytoplasm of the cell.

There are two types of ER.

When ribosomes are attached it is called rough ER and smooth ER when there are no

ribosomes attached.

The rough endoplasmic reticulum is where most protein synthesis occurs in the cell.

The function of the smooth endoplasmic reticulum is to synthesize lipids in the cell.

The smooth ER is also helps in the detoxification of harmful substances in the cell.

Lysosomes

Diagram showing the structure of Golgi and lysosomes.

Lysosomes receive cellular and endocytosed proteins and lipids that need digesting.

The metabolites that result are transported either by vesicles or directly across the

membrane.

Lysosomes basically function as the cell's recycling compartment Golgi Complex

Diagram showing the structure of Golgi complex

It is organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER.

Just like our postal packages which should have a correct shipping address, the proteins produced in the ER, should be correctly sent to their respective address.

In the cell, shipping and sorting done by the Golgi complex. It is a very important step in protein synthesis.

If the Golgi complex makes a mistake in shipping the proteins to the right address, certain functions in the cell may stop.

Vesicles

Vesicles- This term literally means "small vessel". This organelle helps store and transport products produced by the cell.

Some vesicles deliver materials to parts of the cell and others transport materials outside the cell in a process called exocytosis

Cilia

Diagram showing the structure of Cilia

Cilia are thread-like projections of certain cells that beat in a regular fashion to create currents that sweep materials along

Flagella

Diagram showing the structure of flagella

Flagella may extend to the rear of a cell and push it forward by snakelike wriggling, or stick out in front and draw it along.

We humans possess both flagella and cilia. Each sperm cell is propelled by a trailing flagellum that accelerates the little torpedo forward in its quest to fertilize an egg.

Centrosome

Diagram showing the structure of centrosome and centriole

The centrosome, is an area in the cell where microtubules are produced.

Plant and animal cell centrosomes play similar roles in cell division, and both include

collections of microtubules, but the plant cell centrosome is simpler and does not have

centrioles.

During animal cell division, the centrioles replicate (make new copies) and the centrosome

divides.

Centriole (animal cells only)

Diagram showing the structure of centriole

Each centriole is a ring of nine groups of fused microtubules. There are three microtubules in

each group. Microtubules (and centrioles) are part of the cytoskeleton.

In the complete animal cell centrosome, the two centrioles are arranged such that one is

perpendicular to the other.

Questions

Question 1:

The following flow chart illustrates the relationship between two important processes found in the cells

of plants.

a.) Identify the metabolic processes that organelles X and Y control respectively. (2)

b.) Name the carbohydrate that is formed by X and used by Y. (1)

c.) Provide labels for parts A, B and C. (3)

d.) Give ONE structural adaptation of each organelle and describe how this enables the organelle to function efficiently. (4)

[10]

Question 2:

The following diagram illustrates a light microscope used in a Life Sciences laboratory to study microscopic structures. Study the diagram and answer the questions.

a.) The table below contains a list of labels in column A. Match the letters in the diagram with the correct labels and write the letter in column B.

Column A Column B

i. Objective lens

ii. Fine adjustment knob

iii. Body tube

(3)

b.) The table below contains a list of different functions in column A. Match the letters in the

diagram with the correct function and write the letter in column B.

Column A Column B

i. This part moves the body tube to focus the object

clearly.(big movement)

ii. The lower lenses, which are moveable, allowing

you to view objects under different magnification.

iii. This part reflects light onto the slide.

(3)

Question 3:

Consider the following mind map:

Write a paragraph using the mind map above.

Ensure that you include all the topics and bullet points in the mind map.

Your paragraph should not be longer than one page.

The following rubric will be used to mark your paragraph.

Criteria 1 2 3 4 5 Total

Ability to express themselves scientifically

Facts not clear and not linked. Many grammatical errors.

Some flaws of information. Some clear facts. Few errors.

Clear facts, but not all linked yet. Some errors.

Improved linking of facts. Few errors of impact.

Facts clearly expressed and linked. No errors.

Biological correctness and use of terminology.

Confusion. Many biological errors.

Vague understanding and interpretation of mind map.

Adequate understanding and interpretation of mind map.

Almost everything biologically correct.

Mind map perfectly understood and interpreted. Additional info used.

Links

Magnification simulation http://www.cellsalive.com/howbig.htm

Animal / Plant Cell http://www.cellsalive.com/cells/cell_model.htm

3D animation of a cell: http://www.xvivo.net/the-inner-life-of-the-cell/