Bio 102 Exam #2

Cladogram

hypothesis of evolutionary relationships among a group of organisms

- shows what traits animals have in common and what they don't.

Ancestral Characteristics

similarity that is inherited from the most recent common ancestor of an entire group

Derived Characteristic

similarity that arose more recently and is shared only by a subset of the species

- NEW

Outgroup

does not possess any of the derived characteristics

Synapomorphy

derived character shared by clade members

ex) lungs, hair, bipedal

Clade

Species that share a common ancestor as indicated by the possession of shared derived characters

Monophyletic

Pertaining to a group of taxa that consists of a common ancestor and all of its descendants.

- Equivalent to a clade

Characteristics of a virus

have the same basic structure

- nucleic acid core surrounded by a protein

- no cytoplasm/not a cell

Nucleic acid can be DNA or RNA

- circular or linear

- single or double stranded

Classified by genome in part

- could be DNA ,RNA or retrovirus

Viral Structure

- form a protein sheath (capsid) around their nucleic acid core

- some store specialized enzyme with a nucleic acid core

- many animal viruses have an envelope

envelope

a membrane like layer that covers the capsids of some viruses

bacteriophage (aka phage)

a virus that infects bacteria

- diverse and united only by bacterial hosts

ex) e-coli

lytic cycle

Attachment- target part of bacterial outer surfaces

Penetration- T4 pierces cell wall to inject viral genome

Synthesis- phage takes over the cell's replication and protein synthesis enzymes to synthesize viral components

Assembly- assemble components

Release- mature virus particles are released through enzyme that lyses host or budding through host cell wall

Eclipse- time btw absorption and the formation of new viral particles

lysogenic cycle

latent phase; virus does not immediately kill infected cell

- integrate virus into the host cell genome and allows the virus to be replicated along with the host cell's DNA as the host divides.

Prophage

the viral DNA that is embedded in the host cell's DNA

- integrated genome

Influenza vaccine

one of the most lethal viruses in human history

thought to have infected 1/3 of the world's population

the virus is enveloped in animals

types of influenza

A- serious epidemics in humans and other animals (dangerous)

B & C- mild human infections

Antigenic drift

small changes in proteins such that previous vaccine-induced immunity is no longer protective

- This is why we get yearly flu shots, and not a single vaccine

Antigenic shift

- causes pandemics

- flu viruses undergo genetic recombination when 2 strands infect the same cell

ex) bird flu + cow flu = deadly flu no ones been exposed to

HPV and cancer

- cancer causing viruses are rare but deadly

- 70% of cervical cancer cases are caused by sexually transmitted HPV

- viruses can cause cancer by altering the growth properties of human cells

- there are HPV vaccines to prevent cervical cancer

HIV infection cycle

attachment- virus attacks CD4+ cells

entry- through endocytosis

replication- converts viral RNA to double strand DNA

assembly- making many copies of virus

release- new viruses exit by budding

Purpose- destroys certain immune cells

high mutation rate

main reason why there is no vaccine against HIV and infects a broader range of cells

characteristics of a prokaryote

Unicellularity- most are singled celled

cell size- most are less than 1 um in diameter

nucleoid- chromosomes is single circular double-stranded DNA

cell division- most divide by binary fission

genetic recombination- through horizontal gene transfer

internal compartmentalization- no membrane bound organelles

flagella- simple in structure for movement

Types of metabolism for prokaryotes (metabolic diversity)

autotrophs- from inorganic Co2 / make their own food

Photoautotrophs- energy from sun

chemolithoautotrophs- energy from oxidizing inorganic substances

heterotrophs- from organic molecules

photoheterotrophs- light as energy source but obtain organic carbon made by other organisms

Chemoheterotrophs- both carbon atoms and energy from organic molecules ex) humans

3 basic shapes

Bacillus- rod shaped

coccus- spherical

spirillum- helical

Archaea vs bacteria

Plasma Membrane- Archaea has ether linkages and bacteria has ester linkages in

Cell Wall - bacteria has peptidoglycan and archaea has something else

- DNA replication and gene expression in archaea are more similar to eukaryotes, than bacteria is

Gram Stain

A staining method that distinguishes between two different kinds of bacterial cell walls.

gram positive bacteria

thick, complex network of peptidoglycan

stain a purple color

gram negative bacteria

thin layer of peptidoglycan

second outer membrane with lipopolysaccharide

resistant to many antibiotics

stain a pink color because it does not retain the purple color

pili

short, hair like structure

found in gram negative bacteria

aid in attachment and conjugation (hollow tubes for horizontal transfer)

Nucleoid

contains the similar, circular chromosomes (DNA)

may also contain plasmids

Endospores

develop a thick wall around their genome and some of the cytoplasm when exposed to environmental stress

- Highly resistant to extreme environments like heat

when conditions improve, they return to normal cell division

Binary Fission

A form of asexual reproduction in single-celled organisms (prokaryotes) by which one cell divides into two cells of the same size

Plasmid

small, circular piece of DNA located in the cytoplasm of many bacteria

- may encode functions not necessary to the organism, but may provide a selective advantage

horizontal gene transfer

transfer genes to neighboring cells that are not genetically similar

ex) Mrs byzon passing her traits to her students

3 types of horizontal gene transfer

-Conjugation- cell-to-cell contact

-Transformation- from the environment

-Transduction- by viruses

Transformation

- occurs in many bacterial species

- DNA that is released from a dead cell is picked up by another live cell

- natural (environment)

Transduction

Generalized transduction

- virtually any gene can be transferred

- occurs by accidents in the lytic cycle

- Viruses package bacterial DNA and transfer it in a infection

Specialized transduction

- occurs by accidents in the lysogenic cycle

- imprecise excision of prophage DNA

- carry both phage and chromosomal genes

Conjugation

In bacteria, the direct transfer of DNA between two cells that are temporarily joined by hollow pili

Ecological importance

- decomposers release a dead's organism atoms to the environment

- Photosynthesizes fix carbon into sugar

- Nitrogen fixers reduce N2 to NH3 (ammonia) which only bacteria can do

- prokaryotic fermentations can metabolize pyruvate and other compounds to recycle electron donors

define a protist

- most diverse of the four eukaryotic kingdoms (junk pile)

- unicellular, colonial, and multicellular groups

- most are microscopic but some are huge

- all symmetries

- all types of nutrition

types of metabolism in protist

- photosynthetic

- chemoautotrophic

-phagotrophs- ingest particular food matter

- mixotrophs- are both phototrophic and heterotrophic

Choanoflagelate

- unicellular organisms

- fungi and animal common ancestor

- most like the common ancestor of sponges

- have a single emergent flagellum surrounded by a funnel-shaped, contractile collar; structure is exactly matched in sponges, which are animals

Ameoba

- move by means of pseudopods

- free living

- found in soil as well as freshwater

- parasitic

- engulf food particles

- they put a pseudopod forward and then flows into it

- microfilaments of actin and myosin are associated with these movements

Diatom

- phylum chrysophyta

- photosynthetic, unicellular organisms

- unique double shells made of silica

- some move using raphes ( two long grooves lined with vibrating fibrils)

Oomycetes

- water mold

- either parasites or saprobes

- were once fungi

- found in water or on land

- phytophthora infestans (irish potato famine, 400,000 people died)

Plasmodium

- known for causing malaria

- nonwalled, multinucleate mass of cytoplasm

- form called feeding phase

Foraminifera

- heterotrophic marine protist

- pore-studded shells called tests, through which thin podia emerge

- use podia for swimming and feeding

- complex life cycles with haploid and diploid generations

- ex) limestones are rich in forams

Dinoflagellates

- photosynthetic, unicellular with flagella

- live in aquatic environments

- some are luminescent (glow in light)

- do not appear to be directly related to any other phylum

- DNA is not complexed with histones

- asexual

- most have chlorophylls a and c and carotenoids

Ciliate

- feature large numbers of cilia arranged in longitudinal rows or spirals around the cell

- have food (digest) and contractile( water balance) vacuoles

- have a tough but flexible outer covering called a pellicle

Euglena

- 1/3 of these have chloroplasts and are autotrophic

- asexual reproduction; occurs by mitosis

- have 2 anterior and unequal flagella

- have contractile vacuoles which collect excess water

- move towards light called stigma

- have numerous small chloroplast

Plasmodial slime molds

- stream along as a plasmodium

- ingest bacterial and other organic material

- when food or moisture is scarce, organisms forms sporangia, where spores are produced