Concepts, Applications, and Issues 105/Human Bilo… · Lecture Presentation Anne Gasc Hawaii Pacific University and University of Hawaii–Honolulu Community College BIOLOGY OF HUMANS

© 2014 Pearson Education, Inc.

Lecture Presentation

Anne Gasc

Hawaii Pacific University and

University of Hawaii–Honolulu Community College

BIOLOGY OF HUMANSConcepts, Applications, and Issues

Fifth Edition

Judith Goodenough Betty McGuire

3The Cell


The Cell

OUTLINE:

Eukaryotic Cells Compared with Prokaryotic Cells

Cell Size and Microscopy

Cell Structure and Function

Plasma Membrane

Organelles

Cytoskeleton

Cellular Respiration and Fermentation in the Generation of ATP



The Cell Theory is a fundamental organizing

principle of biology that states:

A cell is the smallest unit of life

Cells make up all living things, from unicellular to

multicellular organisms

New cells can arise only from preexisting cells

There are two basic types of cells

Prokaryotic

Eukaryotic



Prokaryotic cells Eukaryotic cells

- Structurally

simpler

- Typically smaller

- Lack membrane-

bound organelles

- Include bacteria

and archaea

- Structurally more

complex

- Typically larger

- Have membrane-bound

organelles

- Found in plants, animals,

fungi, protists


Figure 3.1 A prokaryotic cell.


Figure 3.2 An eukaryotic cell.


TABLE 3.1 Review of Features of Prokaryotic and Eukaryotic Cells



Cells vary in size, but they can never exceed the

volume that can be nourished by materials

passing through the surface membrane

The small size of cells is dictated by a physical

relationship known as the surface-to-volume

ratio

As a cell gets larger, its surface area increases

much more slowly than its volume


Figure 3.3 Cells size and surface area to volume ratio.



Most eukaryotic and prokaryotic cells are

typically measured in micrometers (m) which is

106 meters

They can be seen through either light or electron

microscopes


Figure 3.4 Micrographs are photographs taken through a

microscope.


Cell Structure and Function

Although we begin life as only one cell, that cell

differentiates into many specialized cells

These specialized cells have structures that

reflect their particular functions


Figure 3.5 A cell’s structure reflects its specific function.


Plasma Membrane

The outer boundary of the cell

Controls the movement of substances in and out

of the cell

The phospholipid bilayer separates the

extracellular fluid from the material inside the

cell contained in the cytoplasm

Proteins, cholesterol, and carbohydrates are

also part of the membrane and give it the

qualities of a fluid mosaic


Plasma Membrane

Web Activity: Membrane Structure


Figure 3.6 The structure of the plasma membrane of a cell.


Plasma Membrane Structure

Functions of the plasma membrane

Maintains structural integrity of the cell

Regulates movement of substances into and out of

the cell

Provides recognition between cells (glycoproteins)

Provides communication between cells (receptors)

Sticks cells together to form tissues and organs (cell

adhesion molecules)


Movement Across the Plasma Membrane

Two types:

Passive transport

Movement across the membrane that doesn’t require

energy

Simple diffusion

Facilitated diffusion

Osmosis

Active transport

Movement across the membrane that requires energy


Movement Across the Plasma Membrane

Web Activity: Passive and Active Transport


Simple Diffusion

Movement of a substance following a

concentration gradient: from high concentration

to low concentration

End result is an equal distribution of the

substance in the two areas

Eliminates concentration gradient


Figure 3.7 Simple diffusion.


Facilitated diffusion

Movement of a substance from a region of

higher concentration to a region of lower

concentration with the aid of a membrane

protein

Water-soluble substances need to be assisted or

“facilitated” by certain proteins (carrier proteins)

to cross a cell membrane


Figure 3.8 Facilitated diffusion.


Osmosis

Movement of water across a selectively

permeable membrane from a region of higher

water concentration to a region of lower water

concentration

The water molecules move to dilute the solution


Osmosis

Web Activity: Diffusion and Osmosis


Figure 3.9 Osmosis is the diffusion of water across a selectively

permeable membrane.


Active Transport

Movement often from a region of lower to higher

concentration with the aid of a carrier protein

and energy (usually from ATP)


Figure 3.10 Active transport.


Endocytosis

A region of the plasma membrane engulfs the

substance to be ingested and then pinches off from

the rest of the membrane, enclosing the substances

in a vesicle which travels through the cytoplasm

Applies to large molecules, single-celled organisms,

and droplets of fluid containing dissolved substances

Two types:

Phagocytosis (cell eating)—large particles or bacteria

Pinocytosis (cell drinking)—droplets of fluid


Figure 3.11 Endocytosis—phagocytosis or pinocytosis.


Exocytosis

Large molecules are enclosed in membrane-bound

vesicles that travel to plasma membranes where

they are released to the outside

Exo, exit: outside

Endo: inside


Exocytosis

Web Activity: Endocytosis and Exocytosis


Figure 3.12 Cells package large molecules in membrane-bound

vesicles, which then spill their contents by exocytosis.


TABLE 3.2 Review of Mechanisms of Transport across the

Plasma Membrane


Organelles

Inside eukaryotic cells are membrane-bound organelles that

have different functions

Nonmembranous organelles also perform specific cellular

functions

Organelles include:

Nucleus

Endoplasmic Reticulum

Golgi apparatus

Lysosomes

Mitochondrion


Nucleus

Contains almost all of the genetic information of the cell,

the DNA

Surrounded by a nuclear envelope, which is a double

membrane that allows communication through nuclear

pores

The genetic information is organized into chromosomes

Chromosomes are threadlike structures made of DNA and

associated proteins called histones

Humans have 46 chromosomes (23 pairs) in the loose

form (chromatin) or condensed and are then visible in the

light microscope during cell division


Figure 3.13 The nucleus contains almost all the genetic

information of a cell.


Figure 3.14 Chromosomes are composed of DNA and associated

proteins.


Nucleus

Nucleoplasm

Made of chromatin and the other contents of the

nucleus

Nucleolus

A specialized region within the nucleus

Involved in the production of ribosomal RNA


Endoplasmic Reticulum

An extensive network of channels connected to the

plasma membrane, the nuclear envelope, and certain

organelles

Two types of endoplasmic reticulum

Rough endoplasmic reticulum (RER)

Contains ribosomes that guide the production of cell products

Smooth endoplasmic reticulum (SER)

Lacks ribosomes

Is involved in the production of phospholipids and

detoxification


Figure 3.15 The endoplasmic reticulum (ER) is continuous with the

nuclear membrane and consists of two regions: rough ER and

smooth ER.


Golgi Complex and Lysosomes

Golgi complex

A series of interconnected, flattened membranous

sacs

Cell products are packaged in vesicles and

transferred to the Golgi complex for processing and

packaging

Lysosomes

Contain enzymes that break down macromolecules,

old organelles, and invaders


Figure 3.16 The Golgi complex.


Figure 3.17 The route by which protein-filled vesicles from the rough

endoplasmic reticulum travel to the Golgi complex for processing and

eventual release.


Figure 3.18 Lysosome formation and function in intracellular

digestion.


Mitochondria

Sites of cellular respiration, provide cell with

energy through the breakdown of glucose to

produce ATP

Double-membrane organelle

Contains inner foldings (cristae) that provide

increased membrane surface for cellular respiration

Singular: mitochondrion


Figure 3.19 Mitochondria are sites of energy conversion in the cell.


Cytoskeleton

Provides shape and support for the cell

Is composed of microtubules (thickest),

intermediate filaments, and microfilaments

(thinnest)

Centriole: a microtubule-organizing center located

near the nucleus

Microtubules and microfilaments are seen to

disassemble and reassemble

Intermediate filaments tend to be more

permanent


Centrioles

Organized in a pair of centrioles

Each composed of nine sets of three microtubules

arranged in a ring

May function in cell division and in the formation of

cilia and flagella.


Figure 3.20 Centrioles may play a role in cell division.


Microtubules

Made of the protein tubulin

Responsible for the structure and movement of

cilia and flagella

Cilia are numerous short extensions in a cell that

move back and forth (on cells lining the

respiratory tract)

Flagella are larger than cilia and move in an

undulating manner (In humans, found only on

sperm cells)


Figure 3.21 Microtubules are responsible for the movement of

cilia and flagella.


Microfilaments and Intermediate Filaments

Microfilaments:

Made of the protein actin

Function in muscle contraction

Form a band that pinches cell in two during cell division

Intermediate filaments

Protein composition varies from one type of cell to another

Diverse group of ropelike fibers that maintain cell shape and anchor organelles


Summary of Prokaryotic and Eukaryotic Cell

Structures

Web Activity: Cell Structures


Cellular Respiration and Fermentation in the

Generation of ATP

Cell metabolism

Includes all of the chemical reactions that take

place in a cell

Organized into metabolic pathways

Each contains a series of steps

Specific enzymes speed up each step of the

pathway



Generation of ATP

Both are catabolic pathways that generate cellular

energy

Complex molecules are broken down into simpler

compounds

Energy is released

Cellular respiration requires oxygen to break down

glucose into final products:

Carbon dioxide

Water

Energy



Generation of ATP

Four phases of cellular respiration

Glycolysis

Transition reaction

Citric acid cycle

Electron transport chain

Phases occur continuously in the cell


Cellular Respiration

Phase 1: Glycolysis

Occurs in the cytoplasm

Splits glucose into two pyruvate molecules

Generates a net gain of 2 ATP and 2 NADH

molecules

Does not require oxygen


Figure 3.22 Glycolysis.



Phase 2: Transition reaction

Occurs within the mitochondria

CO2 is removed from each pyruvate

Forms 2 acetyl CoA molecules


Figure 3.23 The transition reaction.



Phase 3: Citric acid cycle or Krebs cycle

Occurs within the mitochondria

Acetyl CoA enters the citric acid cycle

Releases 2 ATP, 2 FADH2, and 6 NADH

molecules

Requires oxygen


Figure 3.24 The citric acid cycle.



Phase 4: Electron transport chain

Occurs within the mitochondria (inner membrane)

Electrons of FADH2 and NADH are transferred

from one protein to another, until they reach

oxygen

Releases energy that results in 32 ATP

Requires oxygen


Figure 3.25 The electron transport chain.


TABLE 3.4 Review of Cellular Respiration


Figure 3.26 Summary of cellular respiration.


Fermentation

Breakdown of glucose without oxygen

Takes place entirely in the cytoplasm

It is very inefficient (compared with cellular

respiration) resulting in only 2 ATP

Lactic acid fermentation takes place in the human

body in muscles during strenuous exercise when the

oxygen supply in the muscle cells runs low

The muscle pain is caused partly by the accumulation

of the waste product lactic acid

The soreness disappears as lactic acid is converted

back to pyruvate in the liver



Generation of ATP

Web Activity: Breaking Down Glucose for Energy


You Should Now Be Able To:

Compare eukaryotic with prokaryotic cells

Understand cell size and microscopy

Describe cell structure and function

Describe the plasma membrane

Know and describe all organelles

Define the cytoskeleton and its structures

Understand and carefully describe cellular respiration and fermentation in the generation of ATP

Documents

Concepts, Applications, and Issues 105/Human Bilo… · Lecture Presentation Anne Gasc Hawaii Pacific University and University of Hawaii–Honolulu Community College BIOLOGY OF HUMANS