Objective 2

Biology

Cell and Cell StructuresCells are: smallest biological unit

that can sustain life.

Two different types of CellsProkaryotes pronounced (pro-carry-

oats)

Prokaryotic cells are one where the genetic material is not contained in a nucleus.

Best Example – E-coli bacteria in your gut

The DNA is just floating in the cell in a ring called a Plasmid.

Pro = beforeKaryo = kernel or seed

“Before the Nucleus”

EuKaryotes pronounced (you-carry-oats)Eu = true

Karyo = kernel or seed

“True Nucleus”

Best example - You

Eukaryotes have genetic material stored in the nucleus. They are:

•generally bigger

•have organelles

•may live in multi-cellular units

Diffusion:Diffusion:

Things moving Things moving from high from high concentration to concentration to low low concentration.concentration.

Things will diffuse until they reach Equilibrium

Osmosis:Osmosis:Water moving across a membrane to equalize another molecule’s concentration.

Example:

A substance (solute) is placed in a beaker that is divided by a semi-permeable membrane.

When a molecule can’t move across a membrane to equalize concentration, Water will!

Water will move to equalize the concentration.

DNA = DeoxyriboNucleic AcidWhat is it made from?

Nucleotides:Phosphate group

Ribose (5 carbon) sugarNitrogen Base

Groups of NucleotidesPurines Pyrimidines

Adenine

Guanine

A

G

Thymine

T

C Cytosine

Pairing Rule1.1.Adenine always bonds with Adenine always bonds with

ThymineThymine

2.2.Guanine always bonds with Guanine always bonds with CytosineCytosine

How do they link up?One Nucleotide links with the next one in the chain by a

COVALENT bond between the ribose and the next nucleotides phosphate

A

C

The opposite side goes in the other direction, linking across the

nitrogen base by HYDROGEN bonds

G

T

How do cells make new copies of DNA for new How do cells make new copies of DNA for new cells?cells?

Replication:1. When DNA needs to be copied,

it unwinds in the nucleus

2. An enzyme, DNA HelicaseDNA Helicase, starts to “unzip” the DNA making a replication fork.3. As DNA is unzipped, another enzyme, DNA PolymeraseDNA Polymerase, begins to add nucleotides to the now exposed bases of the old strand.

4. The two new DNA strands recoil.

DNA making DNA

DNA makes RNA,…….. But How?DNA makes RNA,…….. But How?

Transcription:1. DNA unwinds and unzips.

2. The RNA RNA PolymerasePolymerase attaches to a Initiation site.

4. When reaching a termination site, the RNA Polymerase releases the DNA and goes to make more RNA

3. The RNA Polymerase begins to move only on one (1) of the strands adding RNA nucleotides

DNA making RNA

A c u a a a g c g u a u g c a

Transcription occurs in the nucleus, but the Messenger RNAMessenger RNA (mRNAmRNA) leaves the nucleus.

It attaches to a RibosomeRibosome which begins to read the mRNAIt reads three (3) letter words called Codons

Example: An mRNA that attaches to the Ribosome

It reads ACU, then it moves down and reads AAA and so on…

The process of reading the mRNA code and making Proteins is called:

TranslationThe Ribosome doesn’t just read the mRNA, it calls for Amino Acids for each Codon it reads.

U G C

The codon “U G C” calls for the amino Acid Cysteine.

Hey! I need a Cysteine!! A little help

here?

Help comes from

anotheranother type of RNA:

tRNA

U G C

A C G

Transfer RNAs have a group of three bases called the “anticodon” that is the compliment of the mRNA

Each TRNA carries a different Amino Acid:

ACG carries Cysteine Cysteine

Cysteine

U G C

Threonine

A C G

U G C A C G

Then the ribosome moves to the next Codon

The first tRNA goes away when the second amino acid is attached to the first with a Peptide bond

The Ribosome moves down the mRNA and calls for the next Amino Acid

Cell DivisionCells divide for two reasons.

1. To create copies - Mitosis

2. To create sex cells - Meiosis

Mitosis 4 stages:

1. Prophase:The Centrioles begin to move apart.

Chromosomes thicken

2. Metaphase:The centrioles are at the “poles” of the cellThe chromosomes line up in the middle of the nucleus

The Nuclear membrane disappears

3. Anaphase:The Chromosomes are pulled toward the centrioles by spindle fibers

4. Telophase:The nucleus begins to reform and the cell begins cytokinesis

Meiosis:The process of creating haploid sex cells called Gametes Game

te- sperm or egg

Has Has twotwo “phases” of “phases” of “Mitosis-like “Mitosis-like stages”stages”

For humans, it takes a cell with 46 chromosomes and makes cells with 23.

Let’s look at some Genetic traitsDOMINANT Black color

Recessive lighter color

This dog’s genetics could be two waysWe show the genetics like this:“B” from one parent, “B” from the

other parent

“BB” is Homozygous for the trait.

“B” from one parent, “b” from the other parent

OROR

“Bb” is Heterozygous for the trait.

This dog’s genetics CAN ONLY be shown one way:

“b” from one parent, “b” from the other parentRecessive traits are ALWAYSALWAYS homozygous; thus it would be “bb”

OK, now for a problem:

X

B b b b50% black

50% golden100% golden

You either multiply it out or make a Punnett square50% X 100% =

50%

OrOr b b

B

b

Bb Bb

bb bb

50%

If I have a heterozygous black male and a golden female that mate, what is the chances of having golden puppies in the litter?

Those organisms that are best “fit” to the environment will survive the environment.

Darwin’s Theory - Natural Selection

Extinction – all members of a population dying out due to not having beneficial adaptations.

Adaptation – a characteristic that an organism has that allows it to survive.

EVOLUTION

What Evidence is there for Natural selection?

1. The Fossil Record

Fossils found at lower layers of rock are more simple than those found at upper layers.

2. Homologous Structures.

Structures from one creature are similar to the structures from other creatures.

3. Vestigial OrgansOrgans that are found in you that have no purpose in the body, but are found and used in other organisms. 1. You have an appendix.

2. Snakes have hipbones.

3. Whales have hipbones too.

4. Missing Links

There are missing links in the fossil record that show that the species that are in the earth today.

Rhodocetus – Whale-like species with limbs.

Archaeopteryx – ancient bird-like reptile with wings, and feathers. But it has teeth and claws on the forelimbs.

Sometimes change is directionalDirectional Selection:

This happens when one of the “extremes” is favored in an environment over the other extreme or the old average.

Stabilizing Selection:

Then the average is favored over either of the extremes in a population.

Disruptive Selection:

This situation happens when either extreme is favored over the average.

Virus and Bacteria

Virus: Non-living

Parasitic

Biological Particle

Viruses do not “live” because they can not reproduce outside a “host” cell.Host: - any organism that is used by a virus

or bacteria to complete it’s lifecycle

Bacteria!!!!

Prokaryotic cellsLiving cells!

Bacteria come in three shapes.

Cocci - spherical shaped

Bacilli – rod shaped

Spirilla – corkscrew shaped

Carolus Linnaeuscreated a system that allowed scientist all over the world to name the species that were discoveredKingdom – broadest classification

Phylum – separates into major groups within the Kingdom (plural – phyla)Class – breaks phyla into smaller groupsOrder – more specific

Family – very similar characteristics

Genus – a reproductive grouping

Species – most specific

King

Phillip

Came

Over

For

Good

Soup

ClassificationClassification

How are animals put into the taxonomic categories?They used to be put in by looks (physical Characteristics).

That can cause problems!

Black Bear Koala

Phylogeny- the study of evolutionary relationships

(not bear)

Now organisms are organized by similarities in their DNA.

Cladogram- a way to visually show relationships between organisms.

Two examples

Types of Kingdoms(there are 6 different kingdoms)

1. Animalia- heterotrophicmulti-cellularno cell walls

2. Plantae-Autotrophic

multi-cellular

with cell walls

3 Fungi- Heterotrophic

multi-cellularwith cell wall

4 Protista -Heterotrophic or autotrophic

single cellular Eukaryoticwith or without cell walls

5. Bacteria- heterotrophic or autotrophic

single cellular

prokaryotic

with cell walls

6. Archaebacteria-Heterotrophic or autotrophicsingle cellular

prokaryotic

with cell walls

live in extreme environments