Cell structure Flashcards
what are the seven pillars of life
a programme
improvisation
compartmentation
energy
regeneration
adaptability
seclusion
a programme
organised plan for constitution and regeneration; DNA
improvisation
changing the program as surroundings change; evolution
compartmentation
ability to be separate from environment; membranes
energy
ability to maintain order despite overall positive entropy
regeneration
compensation for environmental wear and tear; repair
adaptability
ability to respond to environmental changes
seclusion
operation of processes and pathways in isolation
ribosome function
protein synthesis
peroxisome function
oxides fatty acids
cytoskeleton function
supports cell, aids in movement of organelles
lysosome function
degrees intracellular debris
transport vesicle function
shuttles lipids and proteins between the ER, Golgi and plasma membrane
Golgi function
processes, packages and targets proteins to other organelles or for export
smooth endoplasmic reticulum function
site of lipid synthesis and drug metabolism
nucleus function
contains the genes (chromatin)
nucleolus function
site of ribosomal RNA synthesis
rough endoplasmic reticulum function
site of protein synthesis
mitochondria function
oxidation of fuels to produce ATP
nuclear envelope function
segregates chromatin (DNA + protein) from the cytoplasm
plasma membrane function
separates cell from environment, regulates movement of materials into and out of the cell
examples of supramolecular complexes
chromatin
plasma membrane
cell wall
examples of macromolecules
DNA
protein
cellulose
examples of monomeric units
nucleotides
amino acids
sugars
which elements do 99% of biological compounds contain
C,H,O,N,P,Ca,S
what are the four major classes of biomolecules
carbohydrates
amino acids
nucleotides
lipids
carbohydrates
glucose, fructose, sucrose
mainly used as sources of cellular energy
amino acids
20 natural amino acids in total
used as protein monomers
nucleotides
5 different types in total
used as parts of DNA and RNA precursors
lipids
known as fats
not very water soluble
used as sources of cellular energy
components of cell membranes
vitamins
organic compounds necessary for proper growth and development
heme
organometallic compound containing iron
important for transporting oxygen in your blood stream
how do enzymes accelerate and control the rates of reaction
greater reaction specificity
milder reaction conditions
capacity for regulation
how are enzymes the agents of metabolic function
metabolites have many potential pathways
enzymes make the desired one the most favourable
cytoplasm
highly viscous solution
many reactions occur
cytoskeleton
contains microtubules
actin filament and intermediate filaments
- cellular shape and division
- intracellular organisation
-intracellular transport paths
-cellular mobility
actin filaments
involved in generating contractile forces
found beneath the plasma membrane
actin rearrangement (polymerisation and depolymerisation) allows the cells to move forwards
microtubules
form the mitotic spindle for the separation of the duplicated chromosomes during mitosis
rapid changes in the actin cytoskeleton allows what
cells to change orientation and direction
phospholipid bilayer
bilayer allows semi-permeability
contains membrane proteins with various functions
name some things located on the plasma membrane
globular proteins
glycoproteins
carbohydrate sugar chain
cholesterol
hydrophilic heads of the phospholipids
hydrophobic tails of the phospholipids
peripheral membrane proteins
integral membrane proteins
cell membrane receptor proteins
the 6 cell membrane roles
transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular joining
attachment
transport
controls entry and exit of materials through carrier and channel proteins
enzymatic activity
enzymes break down macromolecules
signal transduction
send and receive information through ligands and receptors
cell-cell recognition
recognise other cells and pathogens through recognition receptors
intracellular joining
cells are joined to one another through adhesion proteins
attachment
cells are bound to the extracellular matrix by integrin proteins
protein synthesis and sorting
ribosomes are the cells protein making machines
in order for proteins to be functional they need to be transported to their site
this is protein sorting
the localisation of a synthesised protein depends on whether it has a sorting signal
proteins without a sorting signal remain in the cytosol
proteins destined for other organelles including the plasma membrane enter the ER as they’re being synthesised
from the ER proteins are then transported to the Golgi
proteins are then enclosed in transport vesicles to be delivered to their final destination
quality control of proteins and diseases
proteins are synthesised as chains of amino acids
by coiling and folding into a specific three dimensional shape they can perform their biological function
this involves the formation of disulphide bonds catalysed by enzymes residing in the ER
improper folding can have severe consequences for the cell
incorrectly folded proteins exit the ER and are exported to the proteasome for degradation
quality control of low density lipoprotein
their receptors are required for the uptake of cholesterol
mutations of the LDLR cause it to be misfolded and degraded
cystic fibrosis transmembrane conductance regulator CFTR moves acts as a channel for chloride ions
mutant protein retains functionality but it is still recognises as misfolded and is degraded
degradation
cells not only have to synthesise macromolecules but they need to eliminate cellular waste
cellular waste can be in the form of membrane bound signalling proteins which if not removed can signal the cell to divide continually
cells also take up macromolecules such as cholesterol to avoid its excessive build up
cells also degrade unwanted or worn out organelles and macromolecules
specialised immune cells engulf microorganisms and eliminate dying cells
they’re handled by lysosomes through the process of endocytosis
cell endocytose material from the plasma membrane
part of the plasma membrane invaginate enclosing the material then pinches off to form endocytic vesicles
endocytic vesicles fuse with early endoscopes, cargo destined for degradation is retained and incorporated into late endosomes
late endosomes fuse with the lysosomes to deliver cargo for degradation
receptor mediated endocytosis
macromolecules such as glucose, LDL, transferrin (collectively known as ligands) bind to their corresponding plasma membrane receptors
ligand bound receptors clusters on the membrane which invaginate and forms the endocytic vesicles
because the ligand-receptor interaction is very selective it allows the cells to be selective in the materials to internalises
mitochondria supplies energy for cell survival
most of cellular functions that require energy occur in the cytoplasm
however the process of harnessing energy takes place in the mitochondria
energy needs to be transferable and as such cells store energy in the bonds of ATP
mitochondria absorb short carbon chains and oxygen to generate carbon dioxide and ATP
ATP is used to power protein synthesis, transport of molecules against their concentration gradient, muscle contraction, cellular movements
mitochondria can also drive cell death
apoptosis
mitochondria contain cytochrome c
when cells sense damage or any abnormality they activate proteins which form channels in the mitochondrial membrane
through these channels cytochrome c is released which then cause the activation of caspases and subsequently induce apoptosis
nucleus serves as the control centre for cellular functions
houses DNA to code for amino acids to make proteins
DNA controls protein synthesis in essence so therefore cell structure and cell function
fundamental function of the cell is to replicate itself in order to maintain cell populations and ensure tissue homeostasis
requires it to copy its DNA and other cellular components and equally divide into two daughter cells through the cell cycle
cell cycle and mitosis
interphase:
- cellular components are replicated
- G1 and G2 cell duplicates specific molecules and structures
- S cell replicates DNA
mitosis:
-interphase: chromosomes are uncondensed
-prophase: spindle condenses, centrioles appear and the nuclear envelope breaks down
-metaphase: chromosomes align
-anaphase: centromeres and chromatids part
-telophase: spindle disassembles and nuclear envelope reforms
forms two identical diploid daughter cells
