Characteristics of Life

• To be considered living, an organism must…..

1. Be based on a universal genetic code.

– DNA/RNA

– Replication, transcription

2. Grow and develop- Cell division, make proteins, increase in size

Characteristics of Life

3. Be able to reproduce

- Asexually (binary fission)

- Sexually (conjugation, mitosis)

4. Use materials and energy

- Metabolism, respiration

Characteristics of Life5. Be able to respond to their environment

- Stimulus Response

6. Maintain stable internal environment- Homeostasis: getting rid of

unnecessary materials, osmosis, diffusion, cell transport

Characteristics of Life7. Change over time, as a group.

-Evolution, natural selection, adaptation

8. Made of units called cells-Unicellular-Multicellular

unicellular multicellular

BASIC VIRUS NOTES

CHARACTERISTICS OF VIRUSESVIRUS – (POISON) DISCOVERED BY STANLEY – 1935, TMV

• NOT NORMALLY CLASSIFIED (debate on living vs. nonliving)

•CONTAIN GENETIC MATERIAL & PROTEIN

•LIVE AND REPRODUCE ONLY INSIDE OTHER LIVING CELLS•CAUSE DISEASES SUCH AS COLDS, FLU, AIDS, SMALL POX, MEASLES, CHICKEN POX, RABIES, MUMPS AND MONONUCLEOSIS.

• Viruses are pathogens—agents which cause disease

STRUCTURE OF A VIRUS• CORE OF NUCLEIC

ACID AND PROTEIN COAT

• PROTEIN COAT-CAPSID

» NUCLEIC ACID IS EITHER DNA OR RNA

FIVE BASIC SHAPES OF VIRUSES

• HELICAL• SPHERICAL• POLYHEDRAL• BINAL• FILOVIRUS

HELICAL• RNA OR DNA

COILED IN A LONG NARROW CAPSID

• TOBACCO MOSAIC VIRUS

SPHERICAL• TYPICALLY

STUDDED WITH RECEPTORS, MAY BE ENVELOPED (ENVELOPE AROUND CAPSID)

• INFLUENZA (FLU) VIRUS

POLYHEDRAL VIRUS• GEOMETRIC

APPEARANCE

• ADENOVIRUS CAUSES THE COMMON COLD

BINAL• POLYHEDRAL

CAPSID (DNA/RNA)

• HELICAL TAIL

• EX. Bacteriophage

FILOVIRUS

• NO DISTINCT UNIFORM SHAPE

• THREADLIKE LOOPS

• FILOVIRUSFiloviridae Photo Album

• EBOLA• DEADLY VIRUSES

LYTIC CYCLE• VIRUS ENTERS HOST• REPLICATES IMMEDIATELY• PRODUCES MANY NEW VIRUSES• THESE VIRUSES INVADE OTHER CELLS

LYSOGENIC CYCLE

• VIRUS INVADES CELL• DOES NOT

IMMEDIATELY KILL HOST CELL

• BECOMES PART OF HOST’S DNA

• EVENTUALLY GOES INTO LYTIC CYCLE

VIRAL REPLICATION CYCLES

IMPORTANT TERMS1. HOST –

AN ORGANISM THAT SHELTERS AND NOURISHES SOMETHING.

2. RETROVIRUS -A VIRUS THAT REPLICATES BY FIRST TRANSCRIBING RNA INTO DNA. (HIV)

3. VIROID - A SINGLE STRAND OF VIRAL RNA. (PLANT DISEASES)

4. PRION -

VIRAL PROTEIN MOLECULE. CAUSES DISEASES IN ANIMALS. (MAD COW DI-SEASE).

5. CAPSID -

THE PROTEIN COAT OF A VIRUS.

6. PROPHAGE - A VIRAL DNA SEGMENT INSERTED INTO A BACTERIAL CELL

7. LYSIS - THE BREAKING APART OF THE CELL TORELEASE NEW VIRUSES.

A VIRUS THAT ATTACKS A BACTERIA.8. BACTERIOPHAGE