Chapter 7 Cell Structure and Function Unit 3

Chapter 7 Cell Structure and Function Unit 3

Cells Cytology: the study of cells

IMPORTANT CELL STRUCTURES

Cell Theory 1. Cells are made from preexisting cells. 2. Cells are the smallest units of life. 3. All living things are made from at least one cell.

Understanding • Canning and preservation of foods, medical sanitation, sterilization of dental and hospital equipment, use of disinfectants, quarantines against disease… all are base upon the fact that cells are made from preexisting cells. • But, if cells come from preexisting cells, where did the first cells come from?

Cell History

Brief history • • • Hooke (1660’s) Leeuwenhoek (1670’s) Schleiden & Schwann(1830’s) Virchow (1850’s) Brown (1830’s) Margulis (1985)

Robert Hooke • Mid-1600 s • Used microscope to observe living tissues • Named chambers “cells”

Anton van Leeuwenhoek • Mid-1600 s • Used hand lens microscope to observe microscopic life in pond water

German cell biologists 1830 s: Matthias Schleidan: concluded all plants made from cells 1830 s: Theodor Schwann: concluded that all animals made from cells

Rudolph Virchow • 1855 • Concluded that the nucleus was responsible for cell division.

Robert Brown • • 1883 Recognized that cells contained a prominent feature and named it the nucleus.

Louis Pasteur (1860 s) Discovers that Cells come from Cells

Lynn Margulis Born in 1938 proposed the endosymbiotic theory “Organelles in larger, complex cells may have been free-living prokaryotic cells in the past. ” In 2000 she received the U. S. National Medal of Science

Cell theory (based on 200+ years of discoveries) 1. Cells are made from preexisting cells. 2. Cells are the smallest units of life. 3. All living things are made from at least one cell. Cells dividing Brief History of Cells

Microscopy • the use of microscopes to study cells • Different types of microscopes – Light microscope – Transmission electron microscope – Scanning electron microscope

Cells are the basic unit of life • Unicellular: organisms made up of only one cell – Ex: bacteria, protist, fungus • Multicellular: organisms made up of more than one cell – Ex: protist, fungus, plant, animal

ALL CELLS CONTAIN THESE FOUR PARTS… 1. Plasma membrane: cell membrane, made of 2 layers of phospholipids 2. Cytoplasm/Cytosol: a carbohydrate and water based solution located in the cytoplasm that suspends all internal parts of the cell 3. Ribosomes: produces proteins 4. DNA: genetic material made of nucleic acids

Types of cells

There are 2 types of cells • Prokaryote: bacteria, archaebacteria • Eukaryote: protist, fungus, plant, animal

Prokaryotes & Eukaryotes Bacteria pic – Life, p. 459 You carry oats, I eat ‘em! “Pro” = Before “Eu” = True “Karyote” from Greek karyon = Kernal

Prokaryote (bacteria) cell features • • • No nucleus No organelles Small Simple Plasma membrane, ribosome, cytoplasm, DNA Label the bacteria cell in IAN

Prokaryotic (Bacterial) Cell Capsule Label the bacteria cell in IAN on pg. 9

Prokaryotic cell structure • Capsule: durable outer covering that some bacteria have for protection against water, acids, and viruses • Flagella: movement • Cell wall: protective layer around plasma membrane + structural integrity • Pili: anchoring and DNA exchange

Eukaryotic Cell • Complex • 4 basic components + organelles • Organelles: “little organs” that carry out specialized functions within a cell • Many variations

Nucleus • • Directs cell activities Nuclear Envelope (with pores) → outer boundary Chromosomes → (DNA) carry genetic information Nucleolus → (contain RNA) produces ribosomes chromatin

Nucleus • Stores ______ • DNA helps to regulate ______ production. • Proteins ______ cellular activity.

Ribosomes • small structures on endoplasmic reticulum and throughout the cell that function to produce protein Endoplasmic reticulum • an interconnecting system of “pathways, ” for transport. • May be Rough ER (with ribosomes attached) or Smooth ER (without ribosomes attached).

Golgi apparatus (body) • Modify, package, and sort protein packages for secretion, outside of cell • flattened compartments with vesicles for secretion (packaging & shipping)

Lysosome • Organelle that produces enzymes to destroy foreign molecules and waste • small filled sacs, for digestion

Understanding • A student drew this recycling symbol on their notebook cover to represent the lysosome; Why would this be an accurate representation?

Vacuole • Primarily in plants and Protists • Large, compartment for storing liquids – Food, water, salt, or waste

Mitochondria • Organelle responsible for breaking down glucose molecules into ATP energy molecules • They are rod-shaped with folds, for releasing energy (ATP) by respiration

Understanding • Hypothesize which cells would have more mitochondria, cardiac cells or skin cells. • Why?

Chloroplast • Organelle in plants and algae that produces sugar molecules by photosynthesis • Why are chloroplasts green?

Understanding • A student takes a green plant into pitch dark room, closes the door and turns off the light. What color is the plant?

Cytoskeleton • Hollow fibers for support & shape and to move cytoplasm • Made of • Microfilaments • Microtubules Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion

Comparing Cell Structures with Viruses Plant Animal Bacterial Viruses

Bacteria

Plant

Animal

Protist

• Cytoplasm is the chasm • Cytosol fills it up!

Virus

Comparison of Cells to Viruses Cells have: Viruses have: Cells do: Viruses DON’T do:

Comparison of Cells to Viruses Cells have: 1. Membranes 2. Cytoplasm/cytosol 3. Genetic material - DNA 4. Ribosomes Viruses have: 1. Genetic material DNA or RNA 2. Protein coat Cells do: 1. Digestion 2. Excretion 3. Respiration 4. Response to stimuli 5. Need and use energy – metabolism 6. Grow & develop 7. Reproduce themselves Viruses DON’T do: 1. Digestion 2. Excretion 3. Respiration 4. Response to stimuli 5. Need and use energy – metabolism 6. Grow & develop 7. Reproduce themselves