L6 - Intro to the Cell Flashcards
What is the difference between prokaryote cells and eukaryote cells
Eukaryotic cells have membrane-bound organelles and are much larger
Prokaryote cells lack a membrane-bound nucleus
What organelles are apart of the endomembrane system
Nucleus
Endoplasmic Reticulum (smooth and rough)
Golgi apparatus
Lysosomes
Describe the head and tail of the phospholipid layer
Hydrophilic polar heads (phosphate)
Hydrophobic lipid tails (fatty acids)
Describe integral proteins
Proteins that are embedded (either partially) or fully into the membrane
What are peripheral membrane proteins
Proteins that are associated with the membrane, but not actually embedded in it
What is the function of nucleolus
rRNA production, assembly of small and large subunits of ribosomes
What are the functions of the nucleus
To house/protect DNA
Make RNA and assemble ribosomes
Nuclear pores regulate movement of substances in and out
Molecule segregation to allow temporal and spatial control of cell function
Describe the steps of DNA folding to form chromosomes
DNA wrapped 2x around group of 8 histones to form nucleosomes (collectively known as chromatin)
Chromatin condenses to form chromatin fibres then condenses furhter into loops and then stacks as chromosomes
What is the function of ribosomes
Protein production via translation
Where are the two places ribosomes are found in the cell
Free in the cytoplasm - makes proteins to be used in the cytosol
Attatched to the RER - making non-cytosolic proteins/endomembrane
What is the function of RER
Production of:
secreted proteins
membrane proteins
organelle proteins
What happens to proteins in the rough ER
Proteins enter lumen within the RER for folding
Rough ER membrane surrounds the protein to form transport vesicles destined for the Golgi
What is the function of smooth ER
A housing unit for proteins and enzymes
Synthesises lipids including steroids and phospholipids
(Varies greatly from cell to cell)
What is the structure of Golgi apparatus
Complex made up of 3-20 flattened membranous sacs called cisternae, stack ontop of one another
What is the function of the golgi apparatus
Modify, sort, package and transport proteins received from the RER using enzymes in each cisternae
Describe the path of proteins in the golgi apparatus
Proteins move from the cis face to the trans face
What are lysosomes
Vesicles formed from Golgi membrane
Acidic pH
What is the main function of lysosomes
Digestion of:
substances that enter a cell
cell components e.g organelles (autophagy)
Entire cells (autolysis)
What are the parts of the mitochondria
Outer membrane, inner membrane, cristae, matrix, intermembrane space
What is the function of cytoskeleton
Act as scaffolding across the cell
Involved in intracellular transportation and cell movement
What are the three types of fibres in the cytoskeleton (smallest to largest)
Microfilaments
Intermediate filaments
Microtubules
Describe the structure of microfilaments
~7nm in diameter
Comprised of actin molecules assembled in two long chains, twisted around each other
What is the function of microfilaments
Bear tension and weight by anchroing cytoskeleton to plasma membrane proteins
Promote amoeboid motility if required
Are the fibres of the cytoskeleton dynamic
Microfilaments are dynamic
Intermediate filaments are less dynamic
Microtubules are dynamic
Describe the structure of intermediate filaments
8-12nm in diameter
Comprised of diverse range of different materials e.g keratin
What is the function of intermediate filaments
Bear tension and weight throughout cell e.g during cell anchoring
Act as a scaffold for cellular organelles e.g nucleus
Describe the structure of microtubules
Tubular structure
25nm with central lumen of 15nm diameter
Comprised of tubulin dimers (alpha and beta), coiled, to form a tube
What is the function of microtubules
Support cell shape and size
Guide for movement of organelles
Chromosomes organisation - cell division
Support and movement of cilia/flagella
Where are microfilaments found
Around the periphery and lining the interior of cell
Where are intermediate filaments found
In the cytoplasm of the cell
Where are microtubules found
Extends from centriole into cytoplasm / nucleus
