Chapter 4 Cell Structure & Function

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Cells

The basic units of structure and function in all organisms.

Hooke

Named cells after viewing dead empty cork cells- reminded him of monk rooms, also called cells.

Leeuwenhoek

First to observe and record data on living cells.

Schleidon

A Botanist concluded that all plants were composed of cells.

Schwann

A zoologist concluded that all animals were composed of cells.

Virchow

A physician who observed ell division

Cell Theory

The work of these individuals and others were combined into this theory. 1. cells are the basic units of structure and function in all organisms. 2. all organisms are composed of 1 or more cells. 3. Cells come from pre-existing cells through cell division

Virchows Principle

Principle that says that cells come from preexisting cells through the orderly process of cell division.

Cell size

Cells average from 10-50 microns in diameter, they are limited to this size due to their surface area to volume ratio

Surface area

The cells amount of cell membrane. cells obtain all their needs by absorbing them across their cell membrane

Volume

the amount of cellular contents.

Cells Increase in Size

a cells amount of cell membrane (their surface area) increases by the square but their volume increases by the cube. with increased volume the cell has a greater demand for food, oxygen, and produces more waste but its cell membrane (surface area) its to small to handle these increased demands.

Cell Structure or Shape

varies with function ex: Red blood cells are spherical to move through capillaries with least amount of friction. certain types of white blood cells can change their shape to surround and engulf foreign bacteria.

Types of Cells

Prokaryotic and Eukaryotic.

Prokaryotic

cells that lack an organized nucleus and lack membrane- bound organelles.

Membrane- Bound Organelles

a cell part that is covered by a membrane ex. Bacteria.

Eukaryotic

have an organized nucleus and membrane, bound organelles ex. all cells except bacteria

3 major regions of eukaryotic cells

Cell or plasma membrane, cytoplasm, and nucleus

Cell or plasma membrane

separates cells from external environment. It is said to be semi or selectively permeable. the cell membrane is composed of a lipidbilayer with proteins and carbohydrates all with a significant function.

Semi or selectively permeable

it is able to regulate what may enter and exit cell.

Lipidbilayer

2 layers of phospholipids

Water loving lipids orientation

they are orientated so that their polar hydrophilic components are adjacent to aqueous environments.

Aqueous environments

The inner and outer surface of a cell membrane

Hydrophobic lipids

the non-plar, water fearing hydrocarbon chains are positioned away from water, towards the center of cell membrane.

Proteins in lipids

they act as attachment sites for molecules in the extra cellular fluid and they form channels to transport substances in and out of fells

The position of the lipids, proteins, and carbs

they constantly change due to changes in cellular demands throughout the course of each day. because of this ever-changing patterns of organic components in the cell membrane, it is referred to as fluid mosaic model

Fluid Mosaic Model

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

Cytoplasm

The second major region of cells. contains a jelly-like fluid called the cytosol

Cytosol

suspends the organelles

Organelles

the functioning structures in cells

Ribosomes

most numerous of all organelles, unlike most other organelles are not membrane-bound. Their main function is to organize protein synthesis (building)

Endoplasmic Reticulum (E.R.)

folded sacs and tunnels found throughout the cell. Prepares proteins for export and synthesizes steroids

Golgi Apparatus

processes and packages substances produced by the cell. ex. Lysosomes are packaged by the golgi apparatus

Lysosomes

packages of digestive enzymes that digest food molecules and recycle worn-out cell pars, found only in animal cells. Functionally similar to the vacuoles found in plant cells

Mitochondria

carry out cellular respiration- the chemical breakdown of glucose to provide useable energy in the form of ATP which is used to power all cellular activity. These organelles are most numerous in cells with high energy requirements such as muscle cells.

Microtubules and microfilaments

protein rods that shape and support cells forming the cytoskeleton.

Nucleus

stores DNA and synthesizes RNA. Surrounded by a double walled membrane called the nuclear envelope through which substances may enter and exit via nuclear pores. Contains one or more circular organelles called nucleoli which function to synthesize ribosomes.

Nucleoli

circular organelles which function to synthesize ribosomes

Cell Wall

plants. found in addition to a cell membrane, cell wall is outermost covering. Composed primarily of polysaccharides Cellulose

What a cell wall does

... functions to support and protect a cell.

Vacuoles

store water, wastes, enzymes, toxins. they are functionally similar to lysosomes in animal cells.

Plastids

store photosynthesis pigments and other organic compounds.

Types of Plastids

chloroplasts and leucoplasts

Chloroplasts

store photosynthetic pigments called chlorophylls

Leucoplasts

store starches

Levels of Organization

cells make up tissues, tissues make up organs, organs make up organ systems, and organ systems make up multi cellular organism.

Tissues

cells of the same type working together to preform a function

Organ

2 or more different tissues working together to preform a function

Organ System

2 or more different organs

Colonial Organisms

a group of genetically identical cells that live in closely connected groups. Ex: bryozoans

Similarities between colonial organisms and unicellular beasties

Each individual is capable of living independently and do not have tissue and organs

Similarities beween colonial organisms and multicellular beasties

there composed of many cells and do exhibit some cell specialization

Cell specialization

Different cells are able to perform specific tasks

Scanner lens

smallest lens 4 or 5x.

Low Power Lens

10x lens

High Power Lens

40 - 50x lens

Stage

slide is placed there

Diaphragm

regulates light passing through slide

The cell membrane...

is composed mainly of a lipid bilayer

Endoplasmic reticulum (E.R.) and Golgi apparatus

Substances produced in a cell and exported outside of the cell would pass through the...

Mitochondria

cells that have a high energy requirement generally have many...

Lysosomes

Viruses, bacteria, and old organelles that a cell ingests are broken down in...

Nucleus, chloroplasts, and mitochondria

organelles that are surrounded by two membranes and contain DNA are the...

Cilia

short, hair-like structures made of microtubules that enable movement of cells or movement of materials outside a cell

Flagella

long, thin, whip-like structures, with a core of microtubules, that enable some cells to move

What regulates cell size? Why is this so important? What happens when it changes size?

Surface area to volume ratio; through surface area cell gets food and such; surface area to volume changes

Describe the composition, components, and orientation of organic compounds in region 1. Why is the cell membrane called a fluid mosaic model?

Composed of a lipid bilayer with proteins and carbs all with a specific function. Lipids are oriented so their polar, water- loving, hydrophyllic components are adjacent to aqueous environments. The nonpolar , water-fearing hydrocarbon chains are positioned away from water towards the center of the cell membrane. The proteins act as attachment sutes for molecules in the extracellular fluid + they form channels to transport substances in and out of cells; the position of lipids, proteins, and carbs constantly changes due to changes in cellular demands. This ever changing pattern makes it a fluid mosaic model.

Describe 2 differences between prokaryotic and eukaryotic cells. Examples

Prokaryotic cells lack an organized nucleus and membrane- bound organelles eukaryotic have these. Prokaryotic- bacteria. Eukaryotic- anything but bacteria

Rough E.R

has many ribosomes on its surface and is indicative of cells that synthesize numerous proteins for export

Smooth E.R

has few ribosomes on its surface

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