Cell Structure and FunctionChapter 6-10AP Biology

Warm Up Exercise

• Please take a moment to complete the KWL sheet that you picked up as you came in.

• When you finish, complete the pre-lab questions for the lab that we will do later today.

Microscopy• Anton van Leeuwenhoek- first to view

and describe single-celled organisms, “animalcules”

• Robert Hooke- coined the term “cells.”• Types of Microscopes• Light Microscope- used to study living cells.• Scanning Electron Microscope- used for study of the topography (surface) of a specimen.• Transmission Electron Microscope- used to study the internal structure of cells.

• Cell Fractionation- a technique used for studying cells- takes cells apart and separates major organelles from one another.

Cell Theory

• All living things are made of cells.• Cells are the basic unit of structure and

function in living things.• All cells come from pre-existing cells.

Eukaryotic vs. Prokaryotic Cells

• Eukaryotic cells contain DNA in the nucleus. Prokaryotic cells contain DNA in a concentrated region called the nucleoid.

The Plasma Membrane

• Plasma Membrane- a selective barrier (semipermeable) that allows passage of enough oxygen, nutrients, and wastes to and from the cell. • The plasma membrane is a lipid bilayer embedded with diverse proteins.

Surface Area to Volume Ratio

• As you ___________ the cell size, you ____________ the surface area to volume ratio, which ___________ the efficiency of transport across the cell membrane.

Surface Area to Volume Ratio

Animal Cell

Plant Cell

Warm Up Exercise

• Name the three main types of microscopes and what they are used for.• What does cell theory say? • Where is the DNA stored in a

prokaryote?

Nucleus: Information Central• Nucleus- contains cellular

DNA which includes most of the genes in the cell. The nucleus is surrounded by the nuclear envelope.• The nuclear envelope is a double membrane made of 2 lipid bilayers. Includes pore structures that help regulate things entering and exiting the nucleus.• Nuclear Lamina- a net of protein filaments that maintain shape of nucleus and support nuclear envelope.

Nucleus: Information Central• Chromosomes- structures that carry genetic information (DNA). Each chromosome contains one long DNA molecule.• Each eukaryotic species has

a distinct number of chromosomes.

• Chromatin- the complex of DNA and protein making up chromosomes. • Nucleolus- helps synthesize rRNA (ribosomal RNA) and ribosomes.

Ribosomes: Protein Factory

• Ribosomes- made of rRNA and proteins- carry out protein synthesis. • Ribosomes exist as either free ribosomes (suspended in cytosol) or bound ribosomes (attached to the Rough ER or nuclear envelope)

Endoplasmic Reticulum: Biological Factory

• Endoplasmic Reticulum- consists of membranous tubules, and sacs, called cisternae.

• Smooth ER- lacks ribosomes. Functions lipid synthesis, detoxification, and storing calcium ions.

• Rough ER- has ribosomes on surface. Continuous with the nuclear envelope. Synthesizes glycoproteins and other secretory proteins.

Golgi Apparatus: Shipping and Receiving

• Golgi Apparatus- made of flattened membranous sacs called cisternae. Has 2 sides the cis face (receiving) and the trans face (shipping).

Lysosomes: Digestive Compartments

• Lysosome- contains hydrolytic enzymes used to digest molecules.• Phagocytosis- “cell eating”- lysosome digesting food• Autophagy- lysosome breaking down damaged organelles.

Vacuoles: Storage Centers

• Vacuole- functions vary depending on cell type.• Food Vacuole• Contractile Vacuole• Central Vacuole

Mitochondria: Chemical Energy Supercenter

• Mitochondria- site of cellular respiration. • Cellular Respiration- the process that uses O2 to generate ATP by extracting energy from sugars, fats, and other fuels.

Chloroplast: Light Energy Capturer

• Chloroplast- found in plants and algae- the site of photosynthesis. Contain the green pigment chlorophyll.• Is a member of the plastid family- a group of plant organelles.

Endosymbiont Theory

Peroxisomes: Oxidation

• Peroxisomes- contain enzymes that remove hydrogen atoms and transfer them to oxygen, producing hydrogen peroxide (H2O2).

Warm Up Exercise

• Describe the protein’s path through the cell, starting with the mRNA molecule that specifies the protein.

• What sets the limit on how big or how small a cell is?

Cytoskeleton

• Cytoskeleton- a network of fibers extending throughout the cytoplasm- plays a major role in organizing the structure and activities of the cells.•Motor Proteins- allows for cell movement.

Cytoskeleton

• Microtubules- the thickest cytoskeletal fiber, provide a track that organelles with motor proteins can move along. Help separate chromosomes during mitosis. Form flagella and cilia.• Centrosome- region where microtubules are organized. Contains a pair of centrioles. Only in animal cells.

Cytoskeleton

• Microfilaments- the thinnest fiber. Actin and myosin filaments help muscle cells contract. Aide in pseudopodia movement by converting cytoplasm from a liquid to a gel.• Cytoplasmic Streaming- circular flow of cytoplasm within cells. Speeds distribution of cell materials.

Cytoskeleton

• Intermediate Filaments- more permanent fixtures, fix the position of organelles and shape of the cell. Include keratin proteins.

Cell Wall

• Cell Wall- extracellular structure of plant cells. Protects the cell, maintains its shape, and prevents excessive uptake of water. Holds the plant up against gravity.• Primary Cell Wall, Middle Lamella, Secondary Cell

Wall• Plasmodesmata-perforations in the plant cell wall

that allows cytoplasm to be continuous between neighboring plant cells.

Extracellular Matrix• Extracellular Matrix (ECM)- glycoproteins,

carbohydrates and proteoglycans that form strong fibers outside of cells.

Cell Junctions• Tight Junctions- forms a seal around the cell by

pulling neighboring cells close together.• Desmosomes- fasten cells together in strong

sheets.• Gap Junctions- form channels from one cell to

adjacent cell.