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.
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?
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)
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?
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.