Earth and Life Science Grade 11

Earth and Life ScienceChapter 10

BE

ionergetics

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Objectives:When you complete this chapter, you should be able

to:•Examine the principles of cell theory.•Describe the components of cell using a diagram.•Identify the components of the endomembrane system in a eukaryotic cell.•Examine the importance of the endomembrane system in a eukaryotic cell.•Examine the components of a cytoskeleton using diagrams and examples.

•Describe the characteristics and functions of the extracellular matrix in a cell sing an example.•Examine the properties that are unique to living organisms.•Examine the laws of thermodynamics.•Examine the importance of energy to all living organisms.•Examine the characteristics of sunlight.•Examine how the wavelength of light affects photosynthesis.•Examine the role of pigments in photosynthesis.•Describe the process of photosynthesis using a flowchart.•Examine the different methods used by photosynthetic organisms to fix carbon.

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What is a Cell? The cell is the basic unit of structure and function

in living things. Cells vary in their shape size, and arrangements but all cells have similar components, each with a particular function.

Some of the 100 trillion of cells make up human body.

All human cell are microscopic in size, shape and function.

The diameter range from 7.5 micrometer (RBC) to 150 mm (ovum).

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What is a Cell?- Cell is defined as the fundamental living unit of

any organism.

- Cell is important to produce energy for metabolism (all chemical reactions within a cell)

- Cell can mutate (change genetically) as a result of accidental changes in its genetic material (DNA).

- Cytology: the study of the structure and functions of cells.

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Cell History

Cytology- study of cells Used a microscope to examine cork (plant) Hooke called what he saw "Cells“ He described the cells as tiny boxes or a honeycomb He thought that cells only existed in plants and fungi

1665 – Robert Hooke

Cork Cells

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Cell History1673- Anton van Leeuwenhoek

1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants

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Cell History1838 - Matthias Schleiden

A botanist who concluded that all plants are made of cells.

Typical Plant Cell

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Cell History1839 - Theodor Schwann

A zoologist who concluded that all animals are made of cells.

Nerve Cells

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Cell History1858 - Rudolph Virchow1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

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Cell Theory

The COMBINED work of Schleiden, Schwann, and Virchow make up the modern CELL THEORY.

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Cell TheoryThe 3 Basic Components of the Cell Theory were now complete:

1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)

2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)

3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

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Components of All CELLS

1) THE CELL (PLASMA) MEMBRANE The cell membrane is a thin, dynamic

membrane that encloses the cell and controls what enters and leaves the cell.

This membrane separates the cell’s content from the external environment.

It is consist mainly of a Phospholipid Bilayer.

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1) THE CELL (PLASMA) MEMBRANE

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Common Membrane Proteins

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2. CYTOPLASM Is a gel-like matrix of water, enzymes,

nutrients, wastes, and gases and contains cell structures (organelles).

Fluid around the organelles called cytosol.

Most of the cells metabolic reactions occur in the cytoplasm.

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3. DNA (deoxyribonucleic acid)DNA, or deoxyribonucleic acid, contains

the information needed for the creation of proteins (which include enzymes and hormones) and is stored in the nucleus, as already said, in the form of chromatin or chromosomes. The nucleus is the site of DNA duplication, which is needed for cell division (mitosis) and organism reproduction and growth.

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Contraints on CELL Size

A cell exchanges substances with its environment at a rate that keeps pace with its metabolism. These exchanges occur across the plasma membrane, which can handle only so many exchanges at a time. The rate of exchange across a plasma membrane depends on its surface are: “The bigger it is, the more substance can cross it during a given time”. Cell size is limited by a physical relationship called the Surface-to-Volume Ratio. By this ratio, an object’s volume increases with the cube of its diameter, but its surface increases only with the square.

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Contraints on CELL Size

Base on the Picture, when a cell expands in diameter, its volume increases faster that its surface are does.o If the cell gets too big, the inward flow of nutrients and the outward flow of wastes across that membrane will not be fast enough to keep the cell alive.o Surface-to-Volume limits also affects the form of colonial organisms and multicelled bodies.

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The NUCLEUS Brain of Cell Bordered by a porous membrane - nuclear envelope. Contains thin fibers of DNA and protein called Chromatin. Rod Shaped

Chromosomes Contains a small round nucleolus

• produces ribosomal RNA which makes ribosomes.

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The NUCLEUS

2 Important Function:1)It keeps the cell’s genetic

material-DNA-safe from metabolic processes that might damage it.

2)It controls the passage of certain molecules across its membrane.

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The NUCLEUSSTRUCTURE OF THE NUCLEUS

the nuclear envelopenucleoplasmchromatinthe nucleolus

the two major types of

materials

Structure of NucleusNUCLEAR ENVELOPE

The nuclear envelope is a double-layered membrane perforated with pores, which control the flow of material going in and out of the nucleus.

The outer layer is connected to the endoplasmic reticulum, communicating with the cytoplasm of the cell. The exchange of the large molecules (protein and RNA) between the nucleus and cytoplasm happens here.

The inner layer of animal cell nuclei is covered and supported by the nuclear lamina , a dense mesh of fibrous proteins.

The two layer of a nuclear envelope connect at nuclear pores.

Structure of Nucleus

CHROMATIN & CHROMOSOMESChromosomes contain DNA in a condensed form attached to a histone protein.Chromatin is comprised of DNA. There are two types based on function.

Heterochromatin: highly condensed, transcriptionally inactive mostly located adjacent to the nuclear membrane

Eurochromatin: delicate, less condensed organization of chromatin, located in a transcribing cell

Structure of Nucleus

NUCLEOLUS It is an irregularly shaped region, dense with proteins and nucleic acids, where subunits of ribosomes are being produced. The subunits pass through nuclear pores into the cytoplasm, where they join and become active in protein synthesis.

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The ENDOMEMBRANE SYSTEM

It is a series of interacting organelles between the nucleus and the plasma membrane.

MAIN FUNCTIONS:o Is to make lipids, enzymes, and proteins for

insertion into the cell’s membranes or secretion to the external environment.o It is also destroy toxins, recycle wastes, and has other special functions.

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Small, membrane-enclosed sacs called VESICLES form by budding from other organelles or when a patch of plasma membrane sinks into the cytoplasm.

Many types carry substances from one organelle to another:

PEROXISOMES LYSOSOMES ENDOCYTIC and EXOCYTIC CENTRAL VACUOLE

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Vesicles Endocytic and exocytic: Transport or store polypeptides and lipids

Peroxisomes: Digest fatty acids and amino acids; break down toxins and metabolic by-products

Lysosomes: Intracellular digestion (animals)

Central vacuole: Storage; fluid pressure (plants)

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ENDOPLASMIC RETICULUM network of interconnected parallel membranes

(maze), that is continuous with the nuclear membrane;

2. Two types: a. Rough Endoplasmic Reticulum (RER)1. ER studded with ribosomes;2. Function = protein synthesis and intraceluar

transportation of molecules ; b. Smooth Endoplasmic Reticulum (SER)lacks ribosomes;3. Function = lipid & cholesterol synthesis and

Stores calcium.

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Endoplasmic reticulum

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MITOCHONDRIA

Break down organic compounds by aerobic respiration (oxygen-requiring)

Produce ATP kidney-shaped organelle whose inner

membrane is folded into shelf-like partitions called cristae;

"Powerhouse" of the cell = site of cellular respiration where energy is released from glucose.

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CHLOROPLASTS

Produce sugars by photosynthesis

Double membraneCenter section contains grana

Thylakoid (coins) make up the grana.

Stroma - gel-like material surrounding grana

Found in plants and algae.

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CHLOROPLASTS

CHROMOPLASTare plastids that make

and store pigments other than chlorophylls.

AMYLOPLASTare unpigmented

plastids that make and store starch grain.

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CYTOSKELETON

Microtubule

0.25 µm Microfilaments

Framework of the cell Contains small microfilaments and larger microtubules. They support the cell, giving it its shape and help with the movement of its organelles. Is a network of fibers extending throughout the cytoplasm Fibers appear to support the endoplasmic reticulum, mitochondria, and “free” ribosomes

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CYTOSKELETON

FUNCTIONS:

Organizes and moves cell parts

Reinforces cell shape

Interactions between motor proteins and microtubules in cilia, flagella, and pseudopods can move the whole cell

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CYTOSKELETON

Components of the Cytoskeleton

MicrotubulesMicrofilamentsIntermediate filaments

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Components of Cytoskeleton

MICROTUBULE

Are long, hollow cylinders that consist of subunits of the protein tubuli.

They form a dynamic scaffolding for many cellular processes, rapidly assembling when they are needed, disassembling when they are not.

Guide movement of organelles (their function is to move things around in the cell)

Help separate the chromosome copies in dividing cells

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MICROFILAMENTS

Are fibers that consists primarily of subunits of a protein called Actin.

It connect plasma membrane proteins to other proteins inside the cell.

Solid rods of globular proteins. Important component of cytoskeleton which

offers support to cell structure. Microfilaments can slide past each other,

causing shortening of the cell

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MICROFILAMENTS

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INTERMEDIATE FILAMENTS

Are the most stable elements of the cytoskeleton, forming a framework that lends structure and resilience to cells and tissues in multicelled organisms.

Intermediate filaments are twisted protein strands slightly thicker than microfilaments; they form much of the supporting framework in many types of cells.

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MOTOR PROTEINS

are like freight trains, dragging cellular cargo along tracks of microtubules and microfilaments.

Education

Earth and Life Science Grade 11