Structure and Function of Cells

Chapter 4Honors and Lab Biology

Quick Write:

◦Why do we need to learn about cells?

Anticipatory Set!

Burn VictimHealing time is radically reduced and scarring almost eliminated by bioartificial skin!

Cells that do NOT contain membrane bound organelles. (unicellulat)

Prokaryotic cell

Eukaryotic CellCells that DO contain membrane bound organelles.

Cells were discovered due to microscopes in the early 17th century

ROBERT HOOKE 1665 (english scientist) examined a slice of cork, he saw “little boxes” they reminded him of small rooms….cells! These were dead plant cells.

ANTON VAN LEEUWENHOEK 1632-1723 (dutch microscope maker) first to observe living cells

Discovery of Cells….

Is the smallest unit of matter that can carry out all the processes of life.

Organelle: parts within a cell!

Cells

1. All living things are composed of one or more cells

2. Cells are the basic unity of structure and function in an organism

3. Cells come from the reproduction of existing cells.

Cell Theory(150 yrs. Passed after Hooke & Van Leeuwenhoek

Matthias Schleiden (1838) botanist, all plants are composed of cells

Theodor Schwann (1839) zoologist, all animals are composed of cells

Rudolf Virchow (1855) physician, cells come ONLY from other cells.

Three German Scientists early evidence for the cell theory…

Not all cells are alike! They vary in…◦ A) size◦ B) shape◦ C) internal organization

SIZE: range from .2m – 0.2um (most are 10-50um)-not all are microscopic (most are) ex: giraffe’s nerve cells extend 6.5 ft. down it’s leg!!

Cells are limited in size by the ratio between their outer surface area and their volume

Cell Diversity

Organelles: parts of a cell, have specific jobs

Tissues: groups of cells that have a similar function

Internal Organization

TISSUES!!

!

Skin Cells

Death of Tissue

Organ SystemsOrgan systems- a group of organs that work together to perform a set of related tasks. Digestive system includes: the stomach, esophagus, intestines and mouth.

Cells→Tissues→Organs→Organ Systems

Human Circulatory System

Cell Membrane – separates cell from external environment, gives shape and flexibility to cell, selectively permeable

Cell Organelles!

Cytoplasm: ◦ gelatin like aqueous fluid called cytosol◦ Cytoplasmic streaming◦ Mostly water but also salts and organic

molecules

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Mitochondia: power house of the cell! Where cellular respiration occurs, production of ATP, has it’s own DNA◦ Cristae: inner membrane creating many

folds to increase surface area

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Ribosomes: where proteins are made,◦ Free Floating Ribosome: make proteins for

the cell◦ Ribosomes attached to ER: make proteins

to be exported from the cell

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Endoplasmic Reticulum: (ER) acts as a highway for molecules to move around the cell.◦ Smooth ER: does NOT contain ribosomes◦ Rough ER: does contain ribosomes

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Golgi Apparatus (bodies) processes, packages, and secretes

a) product is assembled (moves from ER to golgi, where it is put together and adjusted)

b) product is packaged (in new sacs) c) product is mailed out (sent out of cell)

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Cilia: short hair like projections beat together to move an organism ex: humans trachea cilia move fluids and mucus! YUM

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Flagella: long, whiplike projections, single or in pairs, rapid movement, ex: sperm

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Nucleus: brains! Control center of cell, DNA & RNA are made here!◦ Nuclear envolope: double membrane will pores◦ Chromatin: fine strands of DNA & protein◦ Nucleolus: inside nucleus where ribosomes are

made

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Lysosome: digestive enzymes, digest food, disease causing bacteria, old organelles, ex: lysosomes eat up tissue between fingers in embryos, usually only in animal cells

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Cytoskeleton- helps shape & support cells◦ Microtubules: long slender protein tubes

form spindle fibers during mitosis◦ Microfilaments: fine protein threads

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Centrioles: cell reproduction Centrosome: cell reproduction

Animal cell only!

Animal Cell

Cell Wall: rigid covering made of cellulose, protects cell, goes OUTSIDE cell membrane

Oranelles in Plant Cells ONLY

Central Vacuole: huge structure which may take up 90% of the space in plant cell

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Plastids◦ a) chloroplasts : site for photosynthesis ◦ b) chromoplasts: stores red and yellow

pigment◦ c) leucoplasts: non pigmented

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PLANT CELL