🌱BIO153 TT2 Notes

binary fission

replication process for bacteria, one parent cell divides into two new cells

What are the two man requirements for life?

energy + carbon source

How do photoautotrophs make organic molecules?

from sunlight, water, and CO2

How do chemoheterotrophs use organic molecules?

to extract energy and as a carbon source

Obligate aerobes

require oxygen for survival

Obligate anaerobes

cannot survive when oxygen is present

Facultative anaerobes

can use oxygen when available

How do cyanobacteria use sunlight?

 to produce organic molecules like glucose from CO2

Carbon fixation

chemical energy generated by sunlight gets stored in glucose

Heterocysts

Perform nitrogen fixation (done without oxygen), where N2 from the atmosphere is converted into ammonia. They cannot survive on their own and depend on neighboring vegetation to provide glucose.

Why is nitrogen essential?

it is used to make DNA and proteins, and most organisms depend on ammonia to obtain nitrogen.

What is special about the cell filaments heterocysts have?

They have barriers that block O2 entry, allowing for nitrogen fixation to occur

How can new species of bacteria be identified?

by detecting the 16S rRNA genes in environmental samples

Proteobacteria

gram negative ancestors of eukaryotic mitochondria by endosymbiosis

What type of bacteria are cyanobacteria and how did they originate?

photosynthesizing gram negative ancestors of eukaryotic chloroplasts by endosymbiosis

Coccus

sphere shaped bacteria

Bacillus

rod shaped bacteria

Vibrio

crescent shaped bacteria

Diplo

two cells linked together

Strepto

many cells linked in a chain

Staphylo

many cells in a cluster

Mutualism

a symbiotic relationship where both species benefit

Commensalism

a symbiotic relationship where one species benefits and the other remains unharmed

Parasitism

a symbiotic relationship where one species benefits and the other is harmed

Disease

disturbance in the normal functioning of an organism

Infectious disease

a disease caused by a microorganism (bacteria, eukaryotic protists, fungi, viruses)

Pathogen

a microorganism that causes a specific disease

Obligate pathogen

requires a host to complete its life cycle and causes disease

Opportunistic pathogen

can co-exist as part of an organisms normal microbiome, only begins to cause disease after a trigger (eg. decrease in host’s immune system)

Biofilm

secreted in bacteria by the capsule/slime layer to help with attachment and evasion of host defense

Plasma membrane

made up of a phospholipid bilayer with a hydrophobic inside and a hydrophilic outside

What is able to pass through the plasma membrane?

only O2, CO2, N2 and small molecules can diffuse freely

What type of bacteria has gram positive cell walls?

mostly chemoheterotrophic bacteria

What is the difference between the cell envelope in gram positive and gram negative cell walls?

The gram positive cell wall has a thick layer of peptidoglycan and gram negative has a thin layer of peptidoglycan. Additionally, there is a second lipid bilayer that surrounds the peptidoglycan layer in gram negative bacteria.

What colour does gram positive bacteria appear under a stain?

purple

What colour does gram negative bacteria appear under a stain?

pink

What shape are bacterial chromosomes?

bacterial chromosomes are circular and often accompanied by plasmids

Thylakoid membranes

photosynthetic membranes consisting of folds of lipid bilayer found in cyanobacteria

Carboxysomes

organelles inside bacteria made of a protein shell that convert CO2 into organic molecules

Capsule/slime layer

layer of polysaccharide or protein outside the cell wall

What is the main purpose of the capsule/slime layer?

it allows the bacteria to adhere to surfaces and escape the immune system of the host

Pilus

hair-like structure used in conjugation, allowing for the transfer of DNA between bacteria

Endospores

A dormant, protective structure that some bacteria form to survive harsh conditions. Most commonly found in gram-positive bacteria.

What is peptidoglycan and what is its function?

“Peptides and sugars,” semi permeable membrane that forms a protective structure over the cell wall of most bacteria

What is peptidoglycan made of?

Two types of sugars attached in a long, unbranched chain with a short peptide attached to one of the sugars

What part of the bacteria do antibiotics target?

Peptidoglycan

Unikonta

a supergroup of eukaryotes that includes fungi and animals

SAR

a supergroup of protists, stands for stramenopiles, alveolates, and rhizarians

Archaeplastida

a supergroup of eukaryotes which includes plants and algae

Excavata

a supergroup of protists

What does the common ancestor of unikonta split into?

Amoebozoans and Opisthokonts (fungi/animals)

Which members of the SAR group share an immediate common ancestor?

Stramenopiles and Alveolates

Which two members of Archaeplastida share a common ancestor?

Red algae and green algae

What groups does green algae split off into?

Chlorophytes, Charophytes and Plants

Which groups do Chlorophytes share an immediate common ancestor with?

 Charophytes and Plants

Which group does Excavada share an immediate common ancestor with?

Archaeplastida

Eukaryotes are thought to be descendants of what?

Anaerobic archaea

The first cellular life on Earth was what kind of organism?

Anaerobes

What was behind the oxygen revolution on Earth?

Cyanobacteria conducting photosynthesis

How did organisms develop aerobic respiration?

By adapting to the increased oxygen on Earth produced by cyanobacteria

What is the endosymbiosis theory?

States that eukaryotic organelles were developed by an ancestral eukaryotic cell engulfing an aerobic prokaryote and eventually fusing together

Which domain is eukaryotic mitochondrial DNA placed into?

Bacteria

Which clade is mitochondria placed into based on molecular analysis?

 alpha-proteobacteria

In what ways is mitochondria similar to a gram negative bacteria?

1. Double membrane system

2. Circular DNA

3. Similar ribosomes  

4. Homologous proteins on the inner membrane 

Membrane, DNA, ribosomes, protein (MDRP)

How does endosymbiosis theory explain the evolution of chloroplast?

Cyanobacteria engulfed by eukaryotic cell, cyanobacteria gives host cell the ability to photosynthesize, the two organisms eventually fuse together to form ancestral algae (Archaeplastida)

Based on the endosymbiosis theory, chloroplast evolved from what?

Cyanobacteria

What does cyanobacteria have in common with chloroplast?

1. Both have photosynthetic pathways 

2. Both have systems for transcription and protein translation

What did secondary endosymbiosis accomplish?

it spread photosynthesis to other eukaryotes

What occurred in secondary endosymbiosis?

eukaryotic cell engulfed red and green algae

Exotoxin

toxins produced by pathogenic bacteria which “attack” the host

Endotoxin

outermost layer of gram negative outer membrane which has many sugars attached to it (only produced by gram negative bacteria)

How did cryptophytes develop photosynthesis?

By engulfing red algae

Nucleomorph

a remnant of a nucleus from an endosymbiont found in secondary symbiotic algae

What is contained within the nucleomorph?

DNA surrounded by a nuclear membrane

Which supergroup has nucleomorphs?

Rhizaria from SAR supergroup

Cryptomonad

group of algae which mostly contain plastids (eg. chlorophyll)

What is special about cryptomonads?

Cryptomonads help provide evidence for endosymbiosis due to them having four different genomes, each representing an endosymbiotic event

Nuclear DNA

DNA of the host protist which engulfed the red algae

Mitochondrial DNA

Remains of alpha-proteobacteria genome which got engulfed during mitochondrial endosymbiosis

Think: How did mitochondria develop?

Plastid DNA

Remains of cyanobacterial genome which got engulfed during primary symbiosis

Plastid=Primary Symbiosis

Nucleomorph DNA

Remains of red algae nuclear DNA from secondary symbiosis

Primary endosymbiosis

Eukaryote engulfs prokaryotic cell, leading to the development of organelles such as mitochondria and chloroplasts

Secondary endosymbiosis

Eukaryotic cell engulfs red and green algae, spreading photosynthesis to other eukaryotes

Which organisms evolved from the engulfment of red algae during secondary endosymbiosis?

 Haptophytes, Cryptophytes, Stramenopiles, Alveolates

What supergroup did the engulfment of green algae during secondary endosymbiosis lead to?

Rhizarians and Excavates

What genomes do humans have?

Nuclear DNA and Mitochondrial DNA

What genomes do green algae and plants have?

Nuclear DNA, Mitochondrial DNA, Plastid DNA

What genomes do cryptophytes have?

Nuclear DNA, Mitochondrial DNA, Plastid DNA, Nucleomorph DNA

Algae

 Photosynthetic protists who developed photosynthesis through endosymbiosis, one of the primary producers of oxygen on Earth

Brown algae

Multicellular photoautotrophic stramenopile, similar organs and reproduction cycle to plants

What two groups is green algae split into?

Charophytes and chlorophytes

What similarities do charophytes have to land plants?

• Protein structure in cell wall embedded in plasma membrane 

• Flagellated sperm 

• Nuclear, mitochondrial, and chloroplast DNA

• Sporopollenin (surrounds zygotes/spores to prevent dehydration)

PFDS

What is the difference in the placement of sporopollenin in charophytes versus in plants?

Sporopollenin surrounds zygotes in charophytes and spores in plants

Alternation of generation

plants (and some algae) alternate between sporophyte (diploid) and gametophyte (haploid) stages

Sporophyte

diploid

Gametophyte

haploid

What is the general process for alternation of generation?

Sporophyte → haploid spores → gametophyte → haploid gametes → zygote → sporophyte

SHGHZS (SHanGH ZSang)

Fimbriae

Also known as pili, hairlike projections on the surface of many bacteria that allow them to adhere to surfaces and facilitating biofilm formation.

Bacterial envelope

Separates the cytoplasm from the external environment, made up of the plasma membrane and peptidoglycan cell wall.