Lecture 15: Eukaryotic Cells

Inclusion bodies

Storage granules found in prokaryotic cells that store nutrients/structural materials

Chromatophores – what do they do?

Light-harvesting structures found in photosynthetic bacteria that contain pigments and electron transport components for photosynthesis

eukaryotic equivalent of chromatophores

Chloroplast

Granules

food storage mostly

Sulfur Globules

Store elemental sulfure in bacteria that use sulfur compounds for energy

Gas vacuoles – why are these important for some bacteria?

• Confer buoyancy in planktonic cells by regulating gas levels inside vacuoles

• Help cyanobacteria and other planktonic bacteria adjust their position in water column to reach optimal light/oxygen levels for photosynthesis

Magnetosomes – what are these?

organelles in magnetotactic bacteria that contain magnetic iron particles

magnetosome use

Allow bacteria to sense and align with Earth’s magnetic field, thus helping bacteria navigate to low-oxygen environments in deep water

What are some other inclusion bodies and their use?

• Polyphosphates: accumulations of inorganic phosphate

• Sulfur globules: composed of elemental sulfur

• Magnetosomes: magnetic storage inclusions

• Chromatophores: light harvesting complex

eukaryotes vs prokarytoes - Membrane enclosed organelles

Eukaryotes have while prokaryotes don’t (everything happens in cytoplasm)

eukaryotes vs prokarytoes - Photosynthesis

Occurs in chloroplasts in eukaryotes and occurs in thylakoid membranes/chromatophores in prokaryotes

eukaryotes vs prokarytoes - Skeleton outside or inside

Eukaryotic cells have an internal cytoskeleton made of microtubules, microfilaments, and intermediate filaments while prokaryotes lack a cytoskeleton

eukaryotes vs prokarytoes - Flagella

Eukaryotic flagella made up of microtubules, move in whip-like motion, and are powered by ATP while proakryotic flagella are made up of flagellin protein, move in rotary (propellor-like) motoin, and are powered by PMF

nucleus function

House DNA/direct gene expression

is all DNA in the nucleus

No, mitochondria and chloroplasts have own DNA

nuclear pores function

Allows mRNA, proteins, and ribosomal subunits to enter and leave (for communication purposes)

histones function

Help organize DNA by wrapping it into chromatin

are histones in prokaryotes

No, prokaryotes use nucleoid-associated proteins (NAPs) to organize DNA

What is difference between mitosis vs meiosis?

mitosis

• Function: Growth, repair, sexual reproduction

• Cells that use it: Somatic (body) cells

• End result: 2 identical diploid cells (2n)

meiosis

• Function: Sexual reproduction

• Cells that use it: Gametes (sperm and egg)

• End result: 4 genetically unique haploid cells (n)

Nucleolus – what does this do/make?

Specialized region within nucleus where rRNA is produced

parts of cytoskeleton

microtubules, microfilaments, and intermediate filaments

Microtubules – What are they made of?

Tubulin

Vesicles move along these delivering items throughout the cell, what protein actually walks the vesicles around?

Kinesin and dynein

Microfilaments – made of what? solid, mostly used for cell division

Actin filaments

Intermediate filaments – more permanent, anchors organelles in place, what are these made of?

Keratin

Plasma Membrane of Eukaryotes – what do they have that prokaryotes don’t?

Carbohydrates and sterols

Mitochondria – what is their purpose?

Powerhouse of the cell- produce energy

Cristae inside – more membrane=more energy, what part of metabolism occurs in the mitochondria?

Krebs cycle and ETC/ATP synthesis

Why are two membranes needed for mitochondria?

Outer membrane is protective layer containing porins and inner membrane houses the ETC, creating proton gradient needed for ATP synthesis

How is ATP actually being made in mitochondria?

ATP synthase uses proton gradient to produce ATP via oxidative phosphorylation

mitochondria Came about due to endosymbiosis, what were they once upon a time?

proteobacterium

Hydrogenosomes – what are these?

Similar to mitochondria but lack TCA cycle enzymes and cristae

What type of organism have hydrogenosomes?

Eukaryotic microorganisms that are anaerobic

What do hydrogenosomes help with/produce?

Generatue ATP in anaerobic conditions and produce hydrogen gas instead of CO2

Chloroplasts – what do these do?

Photosynthesis

Chloroplasts Came about due to endosymbiosis, what type of bacteria were they?

cyanobacteria

What component of the chloroplast contains chlorophyll?

thylakoids

Do chloroplasts have their own DNA?

yes

Endoplasmic Reticulum - Smooth vs Rough – difference?

Smooth isn’t covered in ribosomes while rough is

smooth er function

responsible for lipid synthesis and membrane synthesis

rough er function

responsible for protein synthesis and processing

Golgi – Purpose?

Modifies, sorts, and packages proteins and lipids for transport

how is the golgi similar to a Post office?

Sends materials in vesicles to different parts of cell/out of cell

Vacuoles

Stores energy, food, air, water, waste, etc.

Lysosomes – What is their purpose?

Break down waste, old organelles, and bacteria

What is inside of lysosomes

Hydrolytic enzymes (acid hydrolases)

What will lysosomes do to bacterial invaders?

Engulf bacteria via phagocytosis

What will lysosomes do to broken organelles

Autophagy which is the breakdown of damaged organelles for recycling

What is phagocytosis vs exocytosis?

Phagocytosis is engulfing large particles while exocytosis is expelling waste

Flagella – how is the movement different in prokaryotes vs eukaryotes?

Prokaryotic flagella

• Structure: Flagellin protein

• Motion: Rotary (propellor-like)

• Powered by: PMF

Eukaryotic flagella

• Structure: Microtubules (9+2 arrangement)

• Motion: Whip-like (back and forth movement)

• Powered by: ATP hydrolysis

9+2 arrangement, what does this mean?

9 pairs of microtubules surrounding 2 central microtubules

What are microtubules made of?

tubulin

What are cilia?

Short, hair-like structures that move substances/aid movement

Can prokaryotes have cillia?

No, only flagella/pilli

Pseudopods – blob like movements, who does it?

Amoebas, white blood cells

What kind of movement is done by Amoebas?

Cytoplasmic streaming

Cytoplasmic streaming

The cytoplasm inside the cell moves and pushes against the cell membrane.

The membrane extends outward, forming a pseudopod.

The cell anchors the pseudopod and pulls the rest of its body forward.

Cell Wall Components

• NO Peptidoglycan in Eukaryotes

• Plants=Cellulose

• Animals=no cell wall

• Fungi=chitin

Growth by number not size

increase in number of cells, not side of individual bacteria

Most bacteria divide how?

Binary fission (general name: cell division)

What is the septum?

partition/dividing wall that forms in middle of bacterial cell during binary fission

What does generation time mean?

Time it takes for a bacterial population to double