Cell Stucture and Function Flashcards
Prokaryote cell and eukaryote cell both have
Plasma membrane, cytosol, DNA, RNA, protien and ribosomes
Eukaryote cells differ from prokaryote cells because eukaryotic cells have
membrane-bound organelles and are much larger
Prokaryote cells…
lack a membrane-bound nucleus
Cytoplasm including…
organelles
Cytoplasm does not include…
nucleus
The fluid portion of the cytoplasm is the…
cytosol
Prokaryote cells are…
smaller than eukaryote cells
The plasma membrane is …
double layer of phospholipids with embedded proteins
The plasma membrane is …
the physical barrier separates the inside and outside of the cells
Phospholipid has…
hydrophilic polar heads (phosphate)
and
hydrophobic lipid tails (fatty acids)
Phospholipid…
Arranged as a double layer around cytoplasm, tail to tail
The rough Endoplasmic reticulum’s major function is
Secreted proteins
•Membrane proteins
•Organelle proteins
Major organellesinclude:
Nucleus Endoplasmic Reticulum (smooth and rough) Golgi apparatus Lysosomes Mitochondria Ribosomes
Plasma Membrane proteins
Membrane proteins mediate the movement of hydrophilic substances
Plasma Membrane proteins
Are often amphipathic, they have both hydrophilic and hydrophobic regions
Integral proteins
embedded(partially or fully) into the membrane
Transmembrane proteins
integral membrane proteins that fully span the entire membrane, contact extracellular and cytoplasmic areas
Peripheral membrane proteins
associated with the membrane, but not actually embedded in it
What do the plasma membrane proteins do?
- Transport
- Enzymatic activity
- Signal transduction
- cell-cell recognition
- intercellular joining
- attachment to the cytoskeleton and extracellular matrix.
The Fluid Mosaic model
the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
Nucleus
Enclosed by double lipid bilayer called the nuclear envelope, continuous with rough ER
Nucleus
Entry and exit through nuclear pores
Nucleolus
rRNA production, assembly of small and large subunits of ribosomes
Nucleus functions
- to house/protect DNA in eukaryotic cells
- make RNA and assemble ribosomes
- pores regulate the movement of substances (protein and mRNA) in and out
- molecule segregation to allow temporal 时间的and spatial 空间的control of cell function
Ribosomes
two subunits, small and large made of ribosomal RNA (rRNA) in complex with many proteins
Ribosomes function
protein production (translation), found in two places within the cell
Endoplasmic Reticulum
The ER is an extensive network of tubes and tubules, stretching out from the nuclear membrane
Rough Endoplasmic Reticulum
Major functions are the production of:
•Secretedproteins
•Membraneproteins
•Organelleproteins
Rough Endoplasmic Reticulum
Rough ER membrane surrounds the protein to form transport vesicles destined for the Golgi
Smooth Endoplasmic Reticulum
Lacks ribosomes: doesn’t make proteins
Smooth Endoplasmic Reticulum
The major function is as a housing unit for proteins and enzymes
Smooth Endoplasmic Reticulum
The major function is as a housing unit for proteins and enzymes
Golgi apparatus –receiving and modifying
This complex is made up of 3-20 flattened membranous sacs called cisternae, stacked on top of one another (“pita bread”)
Golgi apparatus
Functions:
modify, sort, package and transport proteins received from the rough ER using enzymes in each cisterna
Golgi apparatus –receiving and modifying
Formation of
:•secretory vesicles (proteins for exocytosis)
•membrane vesicles (PM molecules)
•transport vesicles (molecules to lysosome)
Lysosomes [细胞] 溶酶体
contain powerful digestive enzymes
Lysosomes
vesicles formed from Golgi membrane
Lysosomes
membrane proteins pump H+in to maintain acidic pH
Lysosomes
rest of cell protected by the membrane
Lysosomes main functions
The main function is digestion of:
•substances that enter a cell
•cellcomponents e.g. organelles -autophagy
•entire cells -autolysis
Mitochondria
Main function: generation of ATP through cellular respiration
Mitochondria are made up of
- Outermitochondrial membrane
- Innermitochondrial membrane, with folds, called cristae
- Fluid filled interior cavity, called the mitochondrial matrix
Mitochondria – the ATP factory
The transfer of phosphate to another molecule provides energy
Cytoskeleton
the structural support system of the cell
Cytoskeleton
Fibresor filaments that help to maintain the size, shape and integrity of the cell
Three types of fibres (from smallest to largest)
Microfilaments
Intermediate filaments
Microtubules
Cytoskeleton: microfilaments
Diameter: 7 nm Comprised of actin molecules assembled in two long chains, twisted around each other
Found around the periphery and lining the interior of the cell
Cytoskeleton: microfilaments
Function:
Bear tension and weight by anchoring the cytoskeleton to plasma membrane proteins, and promote amoeboid motility if required (eg. macrophage)
Cytoskeleton: intermediate filaments
Diameter: 8-12 nm.
Comprised of the diverse range of different materials; one example: keratin found in the cytoplasm of the cell.
Cytoskeleton: intermediate filaments functions
Function:
•bear tension and weight throughout the cell, e.g., during cell anchoring,
•act as a scaffold for cellular organelles, e.g., the nucleus.
Cytoskeleton: microtubules
Diameter: tubular structure, 25 nm with the central lumen of 15 nm diameter comprised of tubulin dimers (alpha and beta), coiled, to form a tube Extends from centriole into cytoplasm/nucleus
Cytoskeleton: microtubules functions
- Support cell shape and size
- Guide for movement of organelles, •e.g., vesicles from Golgi to membrane
- Chromosome organization – cell division
- Support and movement of cilia/flagella
Cytoskeleton: intermediate filaments
Usually the most permanent of the cytoskeleton
