Ch 3 - Cell Level of Organization Part

8/10/2019 Ch 3 - Cell Level of Organization Part

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Chapter 3: The Cell

Cell theory?


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2 Types of Cells

Sex cells(germ cells):

reproductive cells

male sperm

female oocytes(eggs)

Sex Cells Somatic Cells

Somatic cells(soma

= body):

all body cells except

sex cells

Difference?


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Organelle Functions


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Organelle Functions


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What are the structu res and

funct ions of the cel l membrane?


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Components of the Cell Membrane

Contains lipids, carbohydrates, and functional proteins

Phospholipid Bilayer

Double layer of phospholipid molecules:

hydrophilic headstoward watery environment,

both sides hydrophobic fatty-acid tailsinside membrane

barrier to ions and water soluble compounds

Membrane Proteins

Integral proteins:

within the membrane

Peripheral proteins:

inner or outer surface of the membrane


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6 Functions of Membrane Proteins1. Anchoring proteins(stabilizers):

attach to inside or outside structures

2. Recognition proteins(identifiers):

label cells normal or abnormal

3. Enzymes: catalyze reactions

4. Receptor proteins:

bind and respond to ligands(ions, hormones)

5. Carrier proteins: transport specific solutes through membrane

6. Channels:

regulate water flow and solutes through membrane


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Membrane CarbohydratesProteoglycans, glycoproteins, and glycolipids:

extend outside cell membrane form sticky sugar coat (glycocalyx)

Functions of Membrane Carbohydrates

Lubrication and protectionAnchoring and locomotion

Specificity in binding (receptors)

Recognition (immune response)


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CytoplasmAll materials inside the cell and outside the

nucleus:

cytosol(fluid):

dissolved materials:

nutrients, ions, proteins, and waste products

organelles:structures with specific functions


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What are cel l organel les & their func t ions?

Types of OrganellesNonmembranous organelles:

Do not possess a membrane

In direct contact with cytosol

Membranous organelles:

covered with plasma membrane

isolated from cytosol6 types of nonmembranousorganelles:

cytoskeleton

microvilli

centrioles

cilia

ribosomes

proteasomes

C


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The CytoskeletonStructural proteinsfor shape andstrength

3 types (microfilaments,intermediate, and Microtubules

Microfilaments Thin filamentscomposed of the

protein actin:provide additional mechanical strength

Pairs with thick filamentsof myosinformuscle movement

Intermediate Mid-sized

durable (collagen)

strengthen cell and maintain shape

stabilize organelles

stabilize cell position


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MicrovilliIncrease surface area for absorption

Attach to cytoskeleton


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Centriolesin the Centrosome

Centriolesform spindle

apparatusduring celldivision

Centrosome: cytoplasm

surrounding centriole

CiliaCilia move fluids across thecell surface

Rib


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RibosomesBuild polypeptides in protein

synthesis

Two types:

free ribosomesin cytoplasm:

proteins for cell

fixed ribosomesattached toER:

proteins for secretion

ProteasomesContain enzymes (proteases)

Disassemble damaged proteins for recycling


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Membranous Organelles6 membranousorganelles:

endoplasmic reticulum (ER) golgi apparatus

lysosomes

peroxisomes

mitochondria

nucleus


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Endoplasmic Reticulum (ER)endo= within,plasm= cytoplasm, reticulum= network

Cisternaeare storage chambers within membranes

2 types

Synthesisof proteins, carbohydrates, and lipids

Storageof synthesized molecules and materials

Transportof materials within the ER

Detoxificationof drugs or toxins

Functions of ER


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Smooth Endoplasmic Reticulum (SER)No ribosomes attached

Synthesizes lipids and carbohydrates: phospholipids and cholesterol (membranes)

steroid hormones (reproductive system)

glycerides (storage in liver and fat cells)

glycogen (storage in muscles)

Rough Endoplasmic Reticulum (RER)

Surface covered with ribosomes: active in protein and glycoprotein synthesis

folds polypeptides protein structures

encloses products in transport vesicles


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Golgi ApparatusVesicles enter forming face and exit maturing face

Secretory vesicles:

modify and package products

for exocytosis

Membrane renewalvesicles:

add or remove membrane

components

Transport vesicles:

Carry materials to and

from Golgi apparatus

L

Primary lysosome:


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LysosomesPowerful enzyme-

containing vesicles:

lyso= dissolve,soma= body

Primary lysosome:

formed by Golgi

and inactive

enzymes

Secondary

lysosome:

lysosome fused

with damagedorganelle

digestive

enzymes

activated toxic chemicals

isolatedExocytosis

Ejects secretory products and wastes


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Lysosome FunctionsClean up inside cells:

break down large molecules attack bacteria

recycle damaged organelles

ejects wastes by exocytosis

Self-destruction of damaged cells (Autolysis):

auto= self, lysis= break

lysosome membranes break down

digestive enzymes released

cell decomposes

cellular materials recycle


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Peroxisomes

Are enzyme-containing vesicles:

break down fatty acids, organic compounds

produce hydrogen peroxide (H2O2)

replicate by division

Mit h d i


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Mitochondria

Structure

Figure 39a

Have smooth outer membrane and folded inner

membrane (cristae) - form walls or rooms

Matrix:

fluid around cristae

Mit h d i l F ti


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Mitochondrial Functiontakes chemical energy from food (glucose)

produces energy molecule ATP (Aerobicmetabolism)

Figure 39b

N l


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Nucleus

Is the cells control center

- largest organelleNuclear envelope:

double membranearound the nucleus

Nuclear pores:

communicationpassages

Within the Nucleus


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Within the NucleusDNA:

all information to build and run organisms

Nucleoplasm:

fluid containing ions, enzymes, nucleotides,

and some RNA

Nuclear matrix:

support filaments

Nucleoliin NucleusAre related to protein production

Are made of RNA, enzymes, and histones

Synthesize rRNA and ribosomal subunits


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KEY CONCEPT

Cells: basic structural and functional

units of life

respond to their environment

maintain homeostasis at the cellular level

modify structure and function over time

Organization of DNA


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Organization of DNA

Figure 311

Nucleosomes:

DNA coiled aroundhistones

Chromatin:

loosely coiled DNA

(cells not dividing)

Chromosomes:

tightly coiled DNA

(cells dividing)

What is genet ic code?


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DNA and Genes

DNA: instructions for every protein in the body

Gene:

The instructions for making a single protein

What is genet ic code?

Genetic CodeThe chemical language of DNA instructions:

sequence of bases(A, T, C, G)

triplet code:

3 bases = 1 amino acid


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KEY CONCEPT

The nucleus contains chromosomesChromosomes contain DNA

DNA stores genetic instructions for

proteinsProteins determine cell structure and

function

H d DNA i t t i b t i ?


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How do DNA instruc t ions become proteins?

Protein SynthesisTranscription:

copies instructions from DNA to mRNA (in nucleus)

Translation:

ribosome reads code from mRNA (in cytoplasm)

assembles amino acids into polypeptide chainProcessing:

by RER and Golgi apparatus produces protein


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- DNA contains genetic template" for

proteins.

- DNA is found in the nucleus- Protein synthesis occurs in the

cytoplasm - ribosome.

- "Genetic information" must be

transferred to the cytoplasm where

proteins are synthesized.

problem


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Processes of Protein Synthesis

Transcription- genetic template for

a protein is copied and carried out

to the cytoplasm

Translation- template serves as aseries of codes for the amino acid

sequence of the protein


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Steps of Transcription

1. DNA unwinds

2. One side of DNA "codes for a

protein"3. Genetic code of DNA is a triplet

code of 3 nucleotides or bases

4. Each triplet is specific for thecoding of a single amino acid


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A view of transcription

Fig. 14.12 Brum


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Transcription (cont.)

5. Sequence of triplet codes on DNA will

specify the amino acid sequence on the

protein

6. Major step is the synthesis of the coded"messenger" molecule - mRNA

7. mRNA is "transcribed" from DNA by

complementary base pairing (mRNA hasno thymine, which is replaced by uracil)

8. mRNA passes out to cytoplasm to the

ribosome


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fig. 15.5 from Raven


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Steps in Translation

1. mRNAattaches to the ribosome

2. tRNA'sattach to free amino acids

in the cytoplasmic "pool" of aminoacids

3. tRNAcarries its specific amino

acid to the ribosome


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Translation (cont.)

4. tRNA"delivers" its amino acid based on

complementary pairing of a triplet code

(anticodon) with the triplet code (codon) of

the mRNA.

5. Enzyme "hooks" the amino acid to the last

one in the chain forming a peptide bond.

6. Protein chain continues to grow as each

tRNA brings in its amino acid and adds it

to the chain. - This is translation!!


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U C G UU C A A A

mRNA

A

GC T T CA AAT

GC A A TTG TCodingStran


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U C G UU C A A A

mRNA

A

GC T T CA AAT


Nucleus

Cytoplasm

Ribosome


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A

GC T T CA AAT


Nucleus

Cytoplasm

U C G UU C A A A

U C G UU C A A A

mRNA


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U C G UU C A A A

A

GC T T CA AAT


Nucleus

Cytoplasm


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U C G UU C A A A

A

GC T T CA AAT


Nucleus

Cytoplasm

AA1

AGC

tRNAs


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U C G UU C A A A

A

GC T T CA AAT


AA2

AAG

AA1

AGC

tRNAs

Nucleus

Cytoplasm

ATP


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U C G UU C A A A

A

GC T T CA AAT


AA3

U U U

AA2

AAG

AA1

Nucleus

Cytoplasm

AA1

ATP


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U C G UU C A A A

A

GC T T CA AAT


AA3

U U U

AA2

AAG

AA1

Nucleus

Cytoplasm

AGC

AA1


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U C G UU C A A A

A

GC T T CA AAT


AA3

U U U

AA2

AAG

AA1

Nucleus

Cytoplasm

AGC

AA1


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U C G UU C A A A

A

GC T T CA AAT


AA3

U U U

AA2AA1

Nucleus

Cytoplasm

AGC

AA1

Documents

Ch 3 - Cell Level of Organization Part