Cells, Cell types, Cell features, Organelles Flashcards
Order of size from smallest to largest
Atoms
Small Molecules
Lipids
Proteins
Virus
Bacteria
Organelles
Eukaryotic cells
what are the universal features of Cells.
- What do they require?
- what do they require? why?
- what do they have?
Require genetic information
Require free energy
- To live and r replicate.
Plasma membrane
- Selective barrier
- Concentrate desirable materials e.g. nutrients
- Exclude undesirable materials e.g. waste
products
what is the central dogma of molecular biology.
DNA (hereditary information storage) - DNA synthesis (repliaction)
RNA (Transient info carrier)- RNA synthesis (transcription)
Proteins (e.g. structural; enzymes; transport - Protein Synthesis (translation)
Prokaryotes (6)
- Most diverse
- Small
- 0.2-2μm diameter
- Simple
- Ribosomes in cytosol
- Flagellum
Eukaryotic Cells (7)
- Large - 10 x bigger than prokaryotes
- Complex
- True nucleus with membrane
- Multiple specialised organelles (membrane-bound)
- Larger & complex ribosomes
- Have cytoskeleton for structure and motility
- Large genome (much is ‘irrelevant’)
Yeast 6,300 genes
Nematode Worm 19,000 genes
Humans 25-30,000 genes
what are the common features of Prokaryotes and Eukaryotes (5):
Genetic material (DNA)
Cytoplasm
Plasma membrane
Ribosomes
Similar basic metabolism
what are the membrane bound organelles (8).
Nucleus
mitochondria
ER
Golgi
lysosomes
peroxisomes
chloroplasts
vacuoles
TABLE showing differences.
nucleus
diameter
Membrane bound organelles
Genome
Nucleus
P= Absent
E= Present
Diameter
P= 0.2-2pm
E= 10-100pm
membrane bound Organelles
P= Absent
E= Present
Genome
P= Small
E= Large
Examples of Prokaryotic/ eukaryotic unicellular and Eukaryotic multicellular.
All Prokaryotes are unicellular- Bacteria e.g. E. coli
Eukaryotic unicellular- Yeast e.g. Saccharomyces cerevisiae
Eukaryotic multicellular- Nematode e.g Caenorhabditis elegans
Nucleus (4)
what is it?
what does it contain? (3)
what is it the site of? x2
Most prominent organelle
- (3-10μm)
Contains the genome within
nucleoplasm
chromosomes & proteins
Site of DNA storage
Site of DNA and RNA synthesis
Chromosomes (3)
WHERE!
Not always visible
In the nucleus
Condense and become visible as a cell is about to divide
Nucleolus
what is it?
site of what?
role in what?
membrane?
size?
sub-nuclear structure
- Site of ribosome production
- role in rRNA synthesis
- Not membrane bound
- Variable in size depending on
number of ribosomes produced
what is a nuclear envelope. (4)
what is it?
what does the envolpe have?
what do these do?
what does it provide?
A double lipid bilayer with pores where inner and outer membranes connect.
Envelope is penetrated by pores
Pores act as gates to permit RNA, proteins &
other molecules to move appropriately
Provides QC (=quality control)
- Only mature mRNA leaves the nucleus
what is the nuclear supported by?
what is it composed of?
Supported mechanically by
Fibrous network known as nuclear lamina- composed of intermediate filaments located both Outside and inside the nuclear envelope- provide stability and shape to nucleus.
Endoplasmic Reticulum
Massive membrane system-Interconnecting labyrinth of
branches and flattened sacs
Continuous with nuclear envelope
Central role in lipid and protein biosynthesis and
modification and sorting.
Ribosomes on its surface.
Smooth Endoplasmic Reticulum.
what does it not have?
role?
how does it occur?
involved in what?
without ribosomes
Lipid synthesis and metabolism
Often occurs within regions of RER
Involved in Ca2+ storage (=rapid cellular
responses)
Be able to identify SER and RER
Golgi
works with what?
function?
made of what?
structure?
Works closely with ER
Functions to process, pack & export lipids and proteins
Made of flattened membrane bound
sacs aka cisternae
Two sides and a middle
- Entry side ‘cis’ Golgi (from the ER)
- Middle is ‘medial’ Golgi
- Exit side ‘trans’ Golgi (to the PM)
Golgi
Lipids & protein enter the golgi
Progress through different
cisternae compartments (via transport vesicles) where they undergo further sugar modifications (glycosylation).
they are then Packed in vesicles
these vesicles exit the Golgi apparatus.
They then fuse to subcellular compartments to deliver their contents:
Cell surface membrane
lysosomes- enzymes within lysosomes breaks down/degrades the contents of the vesicles- waste management and recycling
Mitochondria
what does it do?
what does it have?
is it membrane bound organelle?
Energy generation in the cell
Independent genome, ribosomes
Two membranes - Outer & Inner
Inner membrane
- Highly convoluted → Cristae → Large surface
area
- Site of energy generation (ATP)
Label Mitochondria
Lysosomes
type of organelle?
involved in what?
what do they contain?
what do they have to maintain acidity?into what membrane
Acidic organelles
Involved in degradation
- Break down and recycle unwanted organelles (autophagy)
- digest foreign substances that have been phagocytosed (engulfed by the cell) things e.g. bacteria and breaks them down.
Contain acid hydrolases
- a group of enzymes
- work at low (acidic) pH
- break down biomolecules such as proteins, nucleic acid, lipids and carbohydrates.
Proton pump (V-ATPase) and Chloride channel to maintain its acidic environment.
- proton pump= H+
- Chloride channel= Cl-
- H+ and Cl- enter lumen (inside) of
lysosome
- this combination makes it ACIDIC (H+ + Cl- = HCl)
- into the lysosomal memmbrane
USE WORD TO
PRACTICE LABELLING ALL THE ORGANELLES!!
Which ONE of the following components is NOT
found in eukaryotic cells?
1. Rotating flagella
2. Golgi apparatus
3. Mitochondria
4. Endoplasmic reticulum
5. Chromatin
Rotating Flagellum
Which ONE of the following is NOT a common
feature of both prokaryotic and eukaryotic cells?
- Cells are surrounded by a plasma membrane
- Proteins are synthesised by ribosomes
- Genetic information is stored in form of DNA
- RNA is used as a template for protein synthesis
- Cells are surrounded by a rigid cell wall
Cells are surrounded by a rigid cell wall.
Which ONE of the following statements is
INCORRECT?
- The prokaryotic chromosome is usually a circular DNA molecule
- Both prokaryotic and eukaryotic cells are surrounded by a plasma membrane
- The ribosomes are distributed throughout the cytoplasm
- Eukaryotic DNA is coiled up in a region of the cytoplasm
called the nucleoid - Prokaryotic ribosomes are smaller than their eukaryotic counterparts
Eukaryotic DNA is coiled up in a region of the cytoplasm
called the nucleoid.
Which ONE of the following is NOT a membrane-
bound organelle:
- The endoplasmic reticulum
- The Golgi apparatus
- The mitochondrion
- The ribosome
- The lysosome
Ribosomes
Which ONE of the following statements about
cellular structures is INCORRECT?
- The nucleus is the site for the storage of the genetic material
- The smooth endoplasmic reticulum is involved in the biosynthesis of lipids
- The Golgi is involved in packaging and secretion of prokaryotic cell surface proteins
- The mitochondrion is the site of oxidative phosphorylation and ATP synthesis
- The cytoskeleton is present in eukaryotic cells
The Golgi is involved in packaging and secretion of
prokaryotic cell surface proteins.-BEACUSE PROARYOTIC CELL Does NOT HAVE GOLGI.
CYTOKELETON ONLY IN EUKARYOTES!
The pH of lysosomes is lower than that of the
cytosol because of the action of:
- Na+ and OH− transport proteins in the lysosomal
membrane - H+ and Cl− transport proteins in the plasma membrane
- acid-producing enzymes in the lysosomal lumen
- H+ and Cl− transport proteins in the lysosomal membrane
H+ and Cl− transport proteins in the lysosomal membrane.
