Cell Structure and Function Chapter 7. Characteristics of Living Things Page 16.

Cell Structure and Function

Chapter 7

Characteristics of Living Things

Page 16

Levels of OrganizationPage 21

Cell Size and how we know

The Diversity of Cellular Life

Unicellular - single celled organisms, exhibit all the characteristics of life

Can be both Eukaryotic and Prokaryotic

Multicellular - made up of many cells and all cells are interdependent

Each has a specific function that contributes to the whole (specialization of roles)

The Cell Theory

All living things are composed of cellsCells are the basic units of structure and function in living thingsNew cells from existing cells

Two Categories of Cells

Prokaryotes no Nucleussmaller, simpler cellsExample: Bacteria

Eukaryotes Have a NucleusHave Organellesexamples: Plant cells and animal cells (pg 174 fig 7.5)

Comparing Cells

Chart on page 183

Cell Project

Cell Membrane

The cell membrane regulates what enters and leaves the cell and provides protection and support

Cell Membrane (pg 184 fig 7-15)

Phospholipid bilayer

Semi-permeableSome substances can cross and others can’t

Protein molecules run through the lipid bilayerCarbohydrate molecules attached to outer surfaces of proteins

Concentration - mass of solute in a give volume of solutionIsotonic - same strengthHypertonic - above strengthHypotonic - below strength

DiffusionMolecules in solution move constantly and spread randomly through space.They naturally move from an area of high concentration to an area of low concentration until equilibrium is reached.

Equilibrium is reached when the solute is the same throughoutDiffusion does not require energy

Osmosis

The diffusion of water molecules through a biological membraneNaturally moves from a higher concentration to a lower concentration

Will continue until Equilibrium is reachedDoes not require energyOsmotic pressure is on the hypertonic side of a selectively permeable membraneAlmost all cells are hypertonic to fresh water

Facilitated Diffusion

Diffusion that occurs through protein channels in the cell membraneEach channel is specific and allows only certain molecules into the cell

Does not require energyMolecules must flow from a higher concentration to a lower concentration

Active Transport

Molecules move against the concentration difference and flow from a lower concentration to a higher concentrationRequires energy

Examples: Sodium - Potassium pumpEndocytosis - the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane to make a vacuole

Phagocytosis - taking in large particles by endocytosis

Exocytosis - the removal of large amounts of material from a vacuole that fuses with the cell membrane forcing it’s contents out of the cell

Every living cell contains a liquid interior and is surrounded by liquid. Cytosol - a solution of many different substances in waterCytoplasm = cytosol + organelles

Cytoplasm

Cytosol + OrganellesFills the entire cellMade of water, salt and organic substances, also contains enzymes

Cytoplasm

Functions to hold organelles, allows for storage of chemicals, and provides pathways for molecular movement (cytoplasmic streaming)

Cell Wall

Not found in all cellsOutside the cell membraneMade of cellulose – a tough carbohydrate fiber

Cell Wall

Porous enough to allow water, oxygen, carbon dioxide and some other substances through easilyMain function is to provide support and protection for the cell

Nucleus

Largest organelleControl CenterContains DNA

Instructions for everything that goes on in the cell

Nucleic acid that stores and transmits genetic information from one generation to another

DNA

Has to be able to carry info from one generation to another

Structure of DNA

That info needs to determine characteristics Needs to be easy to

copy

Structure of DNA

A long molecule made of nucleotides 5 carbon sugar (ribose) Phosphate group Nitrogenous base

DNA is…

Adenine Cytosine Guanine Thymine

4 Bases

Any sequence is possible Base order = the coded genetic information

Base order

The amount of Adenine is always equal to the amount of Thymine and

Chargaffs’ rule

The amount of Cytosine is always equal to the amount of Guanine

Chargaffs’ rule

Adenine will always pair up with Thymine Cytosine will always pair up with Guanine

Base Pairing

Took x-ray defraction photographs of DNA molecules Noticed a spiral shape

Wilkins and Franklin

Looked at Chargaffs research and photos by Wilkins and Franklin Built a 3 dimensional model of DNA

Watson and Crick

Discovered the shape = Double Helix (2 strands wound around each other) Page 294

Watson and Crick

The DNA SongWe love DNA

Made of nucleotidesSugar, phosphate

and a baseBonded down

one side

Adenine and thymineMake a lovely pair

Cyotsine without guanineWould feel very bare

Sugar and phosphate make sides of the ladder The bases are held together with hydrogen bonds to make the rungs (C=G and A=T)

Like a Ladder

This structure explains how DNA can be copied Each half has the info needed to make the other half (complimentary strands)

Replication

Enzymes unzip the molecule by breaking hydrogen bonds (DNA Polymerase)

Replication

Starts at one point and goes along entire molecule (can go in both directions) Each strand serves as a template for complementary bases

Replication

The result is two DNA molecules identical to each other and to the original molecule

Replication

Coded DNA instructions that control production of proteinsSequence of bases are in the DNA molecule

Genes

Mutations Changes in the DNA

sequence that affect the genetic information

Changes the kind of protein made

Proteins are the keys to almost everything that living cells do

Enzymes, growth regulators, building materials

Proteins

Nucleolus

Makes Ribosomes

Ribosome

Assemble proteins

Step 1 – make RNA

What is RNA?

To make a protein

Required for protein synthesis

Disposable copies of DNALong chains of nucleotides

RNA

Sugar is ribose instead of deoxyribose

Single strand not double Uracil replaces thymine

Different from DNA

Messenger – carries copies of DNA instructions Ribosomal – found in the ribosome Transfer – transfers amino acids to the ribosome

3 Types

The RNA Song

We love RNATranscribed from DNA

Single stands of three kindsM & T & R

M is the messengerT does the transferR is in the ribosome

For translation to occur

RNA and DNAMake a lovely pair

Synthesizing proteins and

Copying part of the nucleotide sequence of DNA into a complementary sequence of RNA

Transcription

Proteins are made of chains of Amino AcidsBases are read in groups of three to code for different Amino Acids

Transcription

the three letter “words” are called codons

Transcription

the three letter “words” are called codonsThere are 64 possible codons that can be made with the 4 bases

Transcription

The decoding of mRNA to form a protein (polypeptide chain)Happens in the Ribosome

Translation

1.mRNA is transcribed from DNA and released into cytoplasm (transcription), then attach to ribosome

To Make a Protein

2. tRNA brings amino acids to the ribosome to match codons

3.Ribosomes form peptide bonds between amino acids and breaks bonds between amino acids and tRNA

To Make a Protein

4. Peptide chain continues to grow until it hits a stop Peptide chain continues to grow until it hits a stop codon that causes it to release from the ribosome and the mRNA molecule

To Make a Protein

Proteins are the keys to almost everything that living cells do

Enzymes, grow regulators, building materials

To Make a Protein

Mutations Changes in the DNA

sequence that affect the genetic information

Changes the kind of protein made

Changes sunlight into food

Changes food into energy

Create Energy

Chloroplasts & Mitochondria

Energy

The ability to do work

All living things depend on Energy

ATP

page 202Figure 8-2Adenosine TriphosphateUsed to store energy needed for life processes

ADP

page 203Figure 8-3Adenosine DiphosphateSimilar in structure to ATP but has only 2 phosphates

Phosphate groups can be added or taken away according to cell supply and needEnergy stored in ATP is released when it is converted into ADP and 1 phosphate group

Uses for ATP in cellsMovement within the cell

organelles along microtubules

Active Transportsodium/potassium pump1 ATP molecule can move 3 sodiums and 2 potassiums

Glucose and ATPCells only keep a small amt of ATP Glucose can store 90x the chemical energy of ATPThey keep larger amounts of glucose

Glucose ATPmore value less valueless mass more mass

Where does the cell get the energy it needs?

PhotosynthesisCellular Respiration

Where do they get it?

AutotrophsHeterotrophs

(carnivore, herbivore, omnivore, decomposer,

scavenger)