CELL ORGANELLES

BACKGROUND INFORMATION

Cells are made up of organelles which means “little organs” Organelles: specialized structures that performs

important cellular functions. There are two main parts of a eukaryotic cell

Nucleus Cytoplasm

PARTS OF THE CELL

Nucleus Ribosomes Endoplasmic Reticulum Golgi Apparatus Lysosomes

Vacuoles Mitochondria Centrioles Cell Membrane Cell Wall Chloroplasts Cytoskeleton

NUCLEUS

Controls most of cell processes and contains the hereditary information of DNA

BRAIN of the cell Contains:

Nucleolus: where assembly of proteins begin Nuclear envelope: Double membrane with pores that

surrounds nucleus Chromatin: consists of DNA tightly coiled around protein

1. Chromatin forms chromosomes when the cell divides

A. Chromosomes contain genetic information

RIBOSOMES Small particles of RNA that make protein They can be found:

A. Alone in cytoplasm- makes proteins for use within the cell

B. Attached to the rough ER- makes proteins for export out of the cell

ENDOPLASMIC RETICULUM Site where lipid

components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell

Two kinds: Smooth ERRough ER

ENDOPLASMIC RETICULUM Rough ER The portion of the

ER involved in the synthesis of proteins

Ribosomes are found on the surface

Smooth ER Ribosomes are not

found on the surface Outer portion of the ER Contains enzymes that

help synthesize lipids and helps in detoxifying drugs

GOLGI APPARATUS Stacked flattened sacks Site where cell products are modified,

sorted, and packaged for storage or export

Involved in the production of lysosomes

LYSOSOMES

Produced by the Golgi apparatus. Small organelles filled with enzymes Functions:

Breakdown of organelles that have outlived their usefulness

They breakdown (recycle) lipids, carbohydrates, and proteins into small molecules that the rest of the cell uses

VACUOLES

The vacuole acts as a container, storing water, salts, proteins, and carbohydrates

Unicellular animals can use vacuoles for movement

Larger in plant cells than animal cells

MITOCHONDRIA Convert chemical energy stored in food

into compounds that are easier for the cells to usePowerhouse of the cellContains fold Structures that need a lot of energy will have

more mitochondria Example: muscle cells

Structure- cristae, outer and inner membranes

CYTOSKELETON

Network of protein filaments that help cells to maintain their shape and for movement

Types: A. microfilaments- produce a tough, flexible

framework that supports cells and helps cells move

B. microtubules- maintain cell shape and are involved in cell division 1. form spindle fibers 2. form centrioles- help organize cell division,

only in animal cells

CENTRIOLES

Found ONLY in ANIMAL cells Cylindrical structures found near the

nucleus Made of hollow, tubular structures

arranged in bundles Important in cell division

CHLOROPLASTS

Capture energy from sunlight and convert it into chemical energy

Contain green pigment called chlorophyll Found ONLY in PLANTS

CELL MEMBRANE Found in ALL cells Provides protection and support for the cell Controls what enters and leaves the cell “Fluid mosaic model”- of cell membrane structure

refers to the many different kinds of molecules in cell membranes- lipids (double layer membrane), protein molecules, and carbohydrate molecules.

CELL WALL Provides support and

protection Found in plant cells Plant cell walls are

made of cellulose-tough carbohydrate fiber

PLANT VS. ANIMAL CELLS

PLANT CELL

ANIMAL CELL

HAVE:Cell WallLARGE

vacuolesChloroplasts

DO NOT HAVE:

Centrioles

Cell membraneMitochondria

Golgi apparatusNucleus

CytoskeletonRibosomes

Endoplasmic reticulum

Lysosomes

HAVE:Centrioles

DO NOT HAVE:Cell Wall

LARGE vacuolesChloroplasts

MOVEMENT ACROSS THE CELL MEMBRANE

TYPES OF CELL MEMBRANE:

Permeable: When all substances cross the membrane

Impermeable: Substances that can’t pass across the membrane

Semi-permeable: “selectively permeable”- some substances can pass across the membrane and some cannot

A. DIFFUSION

The movement of molecules to an area of high concentration to an area of low concentration1. no energy is required to diffuse across the

membrane2. equilibrium- when the concentration of the

solute is the same throughout a system

B. OSMOSIS

The diffusion of water through a selectively permeable membrane (pg 186) 1. isotonic- when the concentration of 2 solutes is the

same inside and outside the cell 2. hypertonic- “above strength”- the solution with the

greater concentration of solutes Animal cells shrink

3. hypotonic- “below strength”- the solution with the lesser concentration of solutes Animal cells swell and burst

C. FACILITATED DIFFUSION

Movement of specific glucose molecules across cell membranes through protein channels that act as carriers to make it easier for certain molecules to cross (pg 187)1. ex- glucose passes through RBC cell

membrane with help of protein channel (only glucose can pass through)

D. ACTIVE TRANSPORT

Transport of materials from an area of low concentration to an area of high concentration which requires energy 1. endocytosis- the process of taking material into the

cell by means of infoldings or pockets of the cell membrane2 Types

A. phagocytosis- “cell eating” – extensions of cytoplasm surround a particle and package it within a food vacuole which the cell engulfs 1. ex- amoeba

B. pinocytosis- process by which a cell takes in a liquid from the surrounding environment

ACTIVE TRANSPORT CONT.

2. exocytosis- process by which a cell releases large amounts of material

III. DIVERSITY OF CELLULAR LIFE

A. Unicellular Organism- single-celled organism 1. They do everything that you expect a living thing to

do:GrowReproduceRespond to stimuliTransform energy

2. more unicellular organisms on Earth than multicellular organisms

3. Ex- yeast, Volvox (alga cells)

EXAMPLES OF UNICELLULAR ORGANSISMS

B. MULTICELLULAR ORGANISMS

Made of many cells 1. cell specialization- cells throughout an

organism can develop in different ways to perform different tasks A. Ex-

RBC- transports oxygen Pancreatic cells- produce proteinMuscle cell- body movement- cytoskeletonStomata- guard cells control the opening and closing

of stomates to exchange CO2, O2, water vapor, and other gases

C. LEVELS OF ORGANIZATION

Cells Tissues Organs Systems 1. tissues- group of similar cells that

perform a particular function 4 main types of tissue:

A. muscle C. epithelial B. nervous D. connective

2. organs- many groups of tissues working together

3. systems- group of organs that work together to perform a specific function