Cell size, Endomembrane system Flashcards
How many cells are there in the human body?
There are 40 trillion cells in the human body
Can diffusion work over large distances?
Diffusion is only effective over small distances
A “random walk” distance is proportional to the square root of time- inefficient over long distances
What organelles do plant cells have that differs them from animal cells? Do they have a sodium potassium pump?
Plant cells have a cell wall, choroplasts and vacuoles. They don’t have a sodium potassium pump
List 4 major processes that take place in the nucleus
- DNA replication
- DNA transcription into mRNA or rRNA
- rRNA folds into 3D structure
- Ribosomes are made of 4 RNAs and about 80 proteins in the nucleolus
How does substances get in and out of nucleus?
TFs, mRNA, ribosomes are transported through nuclear pores
What happens in the rough ER?
Site of translation, rough because there are ribosomes attached
What happens in the smooth ER?
Lipids are made, and site of detoxification
- Liver cells of drug users have more smooth ER
Which side of the Golgi Apparatus faces which direction?
- Cis side faces the ER
- Trans side faces the plasma membrane
What is endocytosis?
When big proteins are able to enter cell and make a big lysosome
What is phagocytosis?
When entire organisms are absorbed into a cell
What is autophagy?
When a damaged organelle is “eaten” in a cell
Where does citric acid cycle take place?
In the matrix of the mitochondria
Where can respiratory enzymes involved in cellular respiration be found?
The invaginations of the mitochondria (cristae)
Where does carbon fixation occur? What does it produce
The stroma
It produces sugar, amino acids and fatty acids
Where do light reactions of photosynthesis take place?
Thylakoid
What are 3 pieces of evidence that mitchondria and chloroplast are descendants of bacteria?
Double membrane
Own genome
Own ribosomes similar to eubacteria
Actin filaments do what? Are they polar or non polar?
- Polar
- They consist of actin + myosin heads- mediate muscle contractions when myosin heads walk along actin filament
What are two types of microtubule? What is the size of a microtubule?
Microtubules are larger than actin
They consist of kinesin and dynein which walk in different directions- organize cells, provide tracks for intracellular transport.
Make up cilia and flagella
What is the purpose of intermediate filaments? What is their size?
Size is between microtubules and actin
They serve mainly for mechanical structure- rope like
What is an epithelium and what is the name for each of its sides?
Epithelium in a sheet of cells
It has an apical side- points towards the gut
Basolateral side points toward interior
4 types of cell-cell junctions
- Tight junction
- Adherens
- Desmosome
- Gap junction
