Lecture 8: Cell Size and Endomembrane Flashcards
Why are cells so small?
-Just waving your arm requires many diffusion process, therefore they must occur on a millisecond scale
-Diffusion is only effective over ver small distances(distance traveled by a defusing molecule is proportional to the square root of time)
-Cells need to be small as it would take way to long for things to diffuse across the membrane
How many cell are found in the human body?
Around 40 trillion
Why can eggs be big?
Because all they do is store stuff
What are prokaryotes?
-Single-celled organism
-Consists of archea and bacteria
Characteristics of prokaryotes?(4)
- Extremely small(same size as an organelle)
- Prokaryotes can live in any environment(they can eat anything(plastic))
- Their DNA sits in a nucleoid not surrounded by a membrane
- Do not have a nucleus
Characteristics of eukaryotes?(4)
- Have a membrane enclosed nucleus that contains DNA (enclosed by a nuclear envelope that consists of two membranes)
- Have organelles enclosed by membranes
- Larger than prokaryotes
- Compartmentalization
Why are eukaryotes so much bigger than prokaryotes?
Due to compartmentalization
What is compartmentalization and why does it make eukaryotes big?
Many internal membrane systems that create very small specialized spaces where diffusion can occur very quickly
Parts found in prokaryotes(4)?
- Plasmid(circular DNA)
- Cell Wall: Provides stability and structure
- Ribosomes: Translate proteins
- Nucleoid: Filled with DNA and proteins
Metabolism of prokaryotes
Prokaryotes can eat anything
- Can use all kinds of different final electron acceptors
Explains why bacteria are found EVERYWHERE
Eukaryotes and metabolism
-Can only use oxygen as the final electron acceptor
-Must eat other plants/animals to survive
Plant cell characteristics
- Rigid cell wall made up of cellulose
- No sodium potassium ATPase(it is unique to animals), plants don’t need osmolarity regulation because they have a rigid cell wall and water can just flow in.
- Modified lysosome called a vacuole
- Chloroplasts
What is the endomembrane system?
Group of membranes and organelles within eukaryotic cells that work together
Compartmentalization and the end-membrane system gives rise to organelles. Name some of the organelles.
- Nucleus
- ER
- Golgi
- Vesicles
- Lysosomes
What organelle does the outer membrane of the nucleus touch?
The ER