cell function and structure Flashcards
what are the 2 main functions of the cell nuclei?
(1) to control chemical reactions within the cytoplasm and
(2) to store information needed for cellular division.
cell nuclei contains what?
chromosomes made of DNA.
what is the endoplasmic reticulum?
The ER is a site of translation, folding & transport of proteins that become the cell membrane as well as proteins that are to be secreted (exocytosed) from the cell.
what does the endoplasmic reticulum do?
ER (endoplasmic “within the cytoplasm”, reticulum “little net”) modifies & makes macromolecules & allows transfer of substances. ER is similar to the plasma membrane.
the endoplasmic reticulum consists of what?
The ER consists of an extensive membrane network of tubes & cisternae (sac-like structures) whilst other parts of the ER membrane are continuous.
Parts of the ER are covered with ribosomes. Their rough appearance under electron microscopy led to their being called rough ER (RER), other parts are free of ribosomes and are called smooth ER (SER).
what are Ribosomes?
A small, ball-like structure in the cell, made of proteins and RNA molecules, that serves as a platform on which the cell’s proteins are made.
what is the Golgi apparatus?
a central delivery system for the cell. It processes proteins targeted to the plasma membrane, lysosomes or endosomes & those that will be secreted from the cell, & sorts them within vesicles.
what are mitochondria and what are its function?
A mitochondrion is an organelle sometimes described as “cellular power plants”, because their primary function is to convert organic materials into energy in the form of ATP.
what are Lysosomes and what are their functions?
functions:
digest food- used to make energy
clean up and recycle-digest broken organelles
structure: membrane sac of digestive enzymes.
what is cytoplasm?
Cytoplasm is a semi-fluid contained inside the plasma membrane. It is composed of ions & soluble macromolecules like enzymes, carbohydrates, salts & proteins.
what is the cytoskeleton and its function?
The cytoskeleton is a cellular “scaffolding” or “skeleton” contained within the cytoplasm. It is a dynamic structure that maintains cell shape, enables some cell motion, and plays important roles in both intra-cellular transport and cellular division.
what are the functions of the plasma membrane?
All cells have a Plasma Membrane that:
Defines the boundary of the cell
Serves as a selective barrier to the passage of molecules, as mediated by highly selective channel & pump proteins
Receives information/stimuli:
-Enables cells to interact with each other eg. cell signalling
Has capacity for movement and expansion:
- Imports and exports molecules, which determines the composition of the cytoplasm
- Distributes membrane lipids to other cell membranes, & to daughter cells when a cell divides
what is the plasma membrane and its function?
Phospholipid bilayer depends on its composition
(eg. cholesterol-rich PM is more rigid than ER membrane, which lacks cholesterol)
Lipid bilayer acts as a permeability membrane
Protein molecules mediate other functions
Plasma Membrane-Transport, simple diffusion, facilitation and active transport
high concentration into low concentration with no energy input, on energy input but moves from low to high and has energy input
diffusion between a high concentration to low concentration is a?
one-way flux
