Biochem Flashcards
No Nucleus definite nucleus; DNA
present but not separate
from the rest of the cell
Prokaryotes
No Mitochondria; enzymes for
oxidation are on plasma
membrane
Prokaryotes
No Endoplasmic
reticulum
Prokaryotes
No chloroplasts; photosynthesis
localized in chromatophores
Prokaryotes
Present (70s): 50s & 30s
Prokaryotes
Present (80s)
60s & 40s
Eukaryotes
Both present in prokaryotes and eukaryotes
Cell membrane
Two great classes of organisms
- Prokaryotes
- Eukaryotes
– to understand life in molecular terms.
- It seeks to describe the structure,
organization, and functions of living
matter in molecular terms.
BIOCHEMISTRY
Parts of The Prokaryotic Cell
- Plasma
membrane - Cell wall
- Cytoplasm
- Cytosol
– Structures and
genetic information
in the form of one
or more DNA are
suspended in it - Ribosomes
– Molecular
machinery for
protein synthesis - Pili
– Aid in attaching the
organism to other
cells or surfaces - Flagella
– Enable cells to swim
– Structures and
genetic information
in the form of one
or more DNA are
suspended in it
Cytosol
– Aid in attaching the
organism to other
cells or surfaces
- Pili
– Molecular
machinery for
protein synthesis
Ribosomes
– Enable cells to swim
- Flagella
composed of
two layers of
phospholipid
molecules
interspersed
with cholesterol
and proteins
The Eukaryotic Cell
Plasma membrane
Membranesurrounded
structures lying
within the
surrounding
cytoplasm
The Eukaryotic Cell
Organelles
- Forms closed
compartments
around cellular
protoplasm to
separate one cell
from another - Has selective
permeabilities and
acts as a protective
barrier to the
uncontrolled flow
of water
The PLASMA MEMBRANE
The PLASMA MEMBRANE
The selective permeabilities for ions
and substrates are provided by:
– transporters and
– ion channels
Specific proteins involved in facilitated
diffusion and active transport
TRANSPORTERS
- carrier is exposed to high
concentrations of solute, and molecules
of solute bind to specific sites - binding induces conformational
change
“PING” STATE
- the conformational change exposes
the carrier to lower concentration of
solute
“PONG” STATE
– Moves one type of molecule
bidirectionally
UNIPORT SYSTEM
– Moves two solutes in the same direction
SYMPORT SYSTEM
– Moves two molecules in opposite
directions (Na+ in, Ca++ out)
ANTIPORT SYSTEM
- Transmembrane
proteins that allow the
entry of various ions - Very selective
– Permitting the passage
of only one type of ion - Activity is controlled by
neurotransmitters
Ion channels
–A specific molecule binds to a receptor
and opens the channel
- LIGAND-GATED
– Open (or close) in response to changes
in the membrane potential
- VOLTAGE-GATED
–Respond to mechanical stimuli
(pressure, touch)
- MECHANICALLY-GATED
The PLASMA MEMBRANE
- Exchanges material with the
extracellular environment by - Plays key roles
exocytosis and endocytosis
- cell-cell
interactions and in transmembrane
signalling
- mutation in the gene encoding LDL receptor
– Familial hypercholesterolemia
- mutation in the gene encoding the CFTR protein, a Cltransporte
– Cystic fibrosis
- mutation in the gene encoding a copper-dependent
ATPase
(Note: Refer to table 40-7 for other diseases)
– Wilson disease
PHOSPHOLIPID
Tails - block large water-soluble molecules from
passing through the membrane while
permitting fat-soluble molecules, including
medications such as tranquilizers and
sleeping pills, to freely cross the membrane
hydrophobic or water hating
PHOSPHOLIPID
Head - anchor the membrane to the cytoplasm the
watery fluid inside the cell, and also to the
water surrounding the cell.
– hydrophilic or water loving
The bilayer contains
both hydrophobic and
hydrophilic regions and
so are termed
“AMPHIPATHIC”
* Saturated fatty acids
have straight tails
whereas unsaturated
fatty acids make kinked
tails
* More kinks in the tail,
the membrane becomes
less tightly packed and therefore more fluid
PHOSPHOLIPIDS
Proteins in PLASMA MEMBRANE
Major functional molecules
consist of;
- Major functional molecules
consist of;
– Enzymes
– Pumps and channels
– Structural components
– Antigens
– Receptors - Over 100 different types
- Carry out a variety of
functions, including
transport of large water
soluble molecules such as
sugars and certain amino
acids.
- Proteins bonded to
carbohydrates - Important integral
membrane proteins, where they play a role in ———
Glycoproteins
- cell-cell interactions
– Enabling the immune system to detect foreign
cells, such as invading bacteria, which carry
different glycoproteins
- Special areas of membrane structures
through which adjacent cells exchange
material - Enable small molecules such as oxygen to
diffuse readily into and out of the cell - The steady stream of oxygen into the cell
enables it to carry out aerobic respiration
(provides the energy needed to carry out
cell functions)
TINY GAPS or GAP
JUNCTIONS
- The “soup” within which all the other cell
organelles reside - Where most of the cellular metabolism
occurs - Mostly water, it is full of proteins that
control cell metabolism including signal
transduction pathways, glycolysis,
intracellular receptors, and transcription
factors.
CYTOSOL
- Resides mainly in the
plasma membrane but
also found in lesser
quantities in
mitochondria, Golgi
complex, and nuclear
membrane - Acts as stabilizer that
limits the movement of
phospholipids layers,
which slide back and
forth in the membrane.
CHOLESTEROL
- This is a collective term for the cytosol
plus the organelles suspended within the
cytosol
CYTOPLASM
Nucleus Contains the cell’s
genetic information
encoded in DNA that
is packaged into ——-
CHROMOSOMES
Within the nucleus
is the —— which
produces ——–
nucleolus
produces ribosomes
Site of aerobic
respiration and the
major site of ATP
synthesis. (Site of
energy yielding
oxidation)
It has its own
DNA
Site of lipid
synthesis and
detoxification.
Mitochondria
- Appears “pebbled” by
electron microscopy due
to the presence of
numerous ribosomes on
its surface - Proteins synthesized on
these ribosomes collect
in the endoplasmic
reticulum for transport
throughout the cell.
Rough ENDOPLASMIC
RETICULUM
- Plays different functions
depending on the
specific cell type
including:
– lipid and steroid
hormone synthesis
– breakdown of lipid- soluble toxins in liver
cells
– control of calcium
release in muscle cell
contraction.
Smooth ENDOPLASMIC
RETICULUM
- It modifies protein
after they are
produced in the
ribosome. - It is involved in the
secretion of
protein from the
cell
Golgi apparatus
- Contains hydrolytic
enzymes necessary for
intracellular digestion - Common in animal
cells, but rare in plant
cells - Hydrolytic enzymes of
plant cells are more
often found in the
vacuole
Lysosome
*Are membrane-bound
packets of oxidative
enzymes
*In plant cells, it
converts fatty acids to
sugar and assists
chloroplasts in
photorespiration
*In animal cells, it
protects the cell from its
own production of toxic
hydrogen peroxide
Peroxisome
A rigid, protective wall made up of
polysaccharides (cellulose, in higher plant
cells)
Provides and maintains the shape of these
cells and serves as a protective barrier.
Fluid collects in the plant cell ——- and
pushes out against the cell wall. This
pressure is responsible for the crispness of
fresh vegetables.
Cell Wall
(plant cells only)
plant cell vacuole
Specialized
organelles found
in all higher plant
cells
Contains the plant
cell’s chlorophyll
responsible for the
plant’s green
color.
CHLOROPLAST
(plant cells only)
Distribution of biomolecules in
a cell (plant)
Cell Wall
Polysaccharide
Distribution of biomolecules in
a cell (plant)
Vacuole
Small molecules
Distribution of biomolecules in
a cell (plant)
Chloroplast
Liquid, protein,
carbohydrates
Chemical Elements of
Cells
Most abundant:
– Hydrogen (60%)
– Oxygen (25%)
– Carbon (12%)
– Nitrogen (5%)
Other notable elements occurring
in small quantities includes P, S,
Ca, Mg, Na, Cl and trace amounts
of Fe, Cu, Mn etc.
- Molecules that
naturally occur in
living organisms - Large or giant
molecules
(macromolecules) - Composed of polymers
Biomolecules
FOUR MAJOR BIOMOLECULES
- Proteins (amino acids)
- Carbohydrates
(monosaccharides) - Nucleic acids (nucleotides)
- Lipids (fatty acids)
– simple subunits;
building blocks
Ex. Amino acid, Nucleotide, Saccharide
Monomers
– made by joining monomers
Ex.
– Peptide, Oligopeptide, Polypeptide,
Protein
– Nucleic acid, i.e. DNA, RNA
– Oligosaccharide, Polysaccharide
Polymers
Composition of Biomolecules
- CARBOHYDRATES
– Monosaccharides (glucose, galactose, fructose)
– Oligosaccharides (sucrose, maltose, lactose)
– Polysaccharides (cellulose, starch, glycogen)
- Fatty acids
*Long-chain
monocarboxylic
acids
*Have a general
structure of
CH3(CH2)nCOOH
L I p I d s
- are lipids possessing a glycerol
with one or more fatty acyl
groups - Glycerol - (propan-1, 2, 3-triol)
GLYCERIDES
Three parts
1. A five carbon sugar
2. A base that has a nitrogen (N)
atom
3. An ion of phosphoric acid
Nucleotide
five (5) nucleotide bases
Adenine
Thymine
Uracil
Cytosine
Guanine
NUCLEIC ACIDS DNA
DNA
* 4 nitrogenous base
A, T, C, G
* Deoxyribose (sugar)
+ Phosphate group
– Combinations of 20 amino acids
– Protein chains are polypeptides
– Macromolecule – increasing
dimensional complexity : primary,
secondary, tertiary & quaternary
PROTEINS
NUCLEIC ACIDS RNA
- 4 nucleotides base
A, U, C, G - Ribose (sugar) +
Phosphate group
invented one of the microscope’s first prototypes.
1600’s
Zacharias Janssen
first clear drawings of the plant cells he had observed in thin cells of cork. He first coined the term “cell” which reminded him of the many box-like structures (blocks of cells) occupied by the monks.
1665
Robert Hooke
discovery of blood cells, sperm cells, and a lively world of “animalcules” which were later found to be bacteria and protozoans. Also, he created his own powerful microscope. The cell theory was only formulated after nearly 200 years since the introduction of microscopy.
1673
Antonie van Leeuwenhoek
all organisms originate from and consist of cells. This became the initial statement of the modern cell theory. Three significant discoveries during the 1830s led to the early development of the cell theory.
1779-1851
Lorenz Oken
discovered the nucleus as a constant part of the plant cell. Then the nuclei were also found and observed in some animal cells.
1833
Robert Brown
first recognized the living substance within the cell which he termed “sarcode”.
1835
Felix Dujardin
This term was later changed to protoplasm by a Czech physiologist ——————, referring to the colloidal substance in the cell.
1835
Jan Evangelista Purkinje
cells are the elementary particles of both plants and animals. They noted that some organisms are unicellular while others are multicellular.
1838-1839
Matthias Jakob Schleiden
&
Theodore Schwann
the cell is the basic and structural unit of life and that every cell is formed from a preexisting cell.
1858
Rudolf Virchow
Large structure surrounded by a double membrane.
Function:
storage of genetic information
synthesis of DNA and RNA
Nucleus
granular body within the nucleus consists of RNA protein.
Function:
site for ribosomal RNA synthesis
ribosome subunit assembly
Nucleolus
composed of a complex of DNA and protein known as chromatin.
condense during cell division, becoming visible as rod-like chromosomes.
Function:
contain genes (units of hereditary information) that govern the structure and activity of cells.
Chromosomes
contain cellulose fibrils (found in plants, prokaryotes, fungi, and some protists).
Function:
protection, maintaining cell shape
prevents excessive uptake of water
Cell Wall
membrane boundary of the cell
Function:
encloses cellular contents and regulates movement of materials in and out of the cell. help maintain cell shapes and communicate with other cells.
Plasma Membrane
membranous sacs (mostly in plants, fungi, algae).
Function:
store materials, wastes, water
maintain hydrostatic pressure
Vacuoles
membranous sacs (in animals)
Function:
contain enzymes to break ingested materials, secretions, and wastes.
Lysosomes
stacks of flattened membrane sacs
Function:
modifies protein packages secreted proteins.
sorts other to vacuoles and other organelles.
Golgi Complex
granules composed of RNA and protein
some attached to ER, some free in the cytosol.
Function:
synthesize polypeptides in both prokaryotes and eukaryotes.
Ribosomes
ribosomes stud outer surface
Function:
manufacture of many proteins destined for secretion or incorporation into membranes.
Rough ER
lacks ribosomes on the outer surface
Function:
lipid biosynthesis
Smooth ER
network of internal membranes
extending through cytoplasm
Function:
synthesize lipids and modify many proteins
origin of intracellular transport vesicles that carry proteins
Endoplasmic Reticulum (ER)
membranous sacs containing a variety of enzymes.
Function:
site of many diverse metabolic reactions.
Peroxisomes
sacs consisting of two membranes
inner membrane is folded to form cristae and encloses matrix.
Function:
site of most reactions of cellular respiration.
transformation of energy originating from glucose or lipids into ATP energy.
Mitochondria
double-membrane structured enclosing material thylakoid membranes.
chloroplasts contain chlorophyll in thylakoid membranes.
Function:
site of photosynthesis chlorophyll captures light energy.
ATP and other energy-rich compounds are formed and used to convert CO2 to glucose.
Plastids (e.g. chloroplast)
hollow tubes made of subunits of tubulin protein.
Function:
provide structural support.
have a role in cell and organelle movement and cell division.
components of cilia, flagella, centrioles, basal bodies.
Microtubules
solid, rod-like structures consisting of actin protein.
Function:
provide structural support.
play a role in cell and organelle movement and cell division.
Microfilaments
tough fibers made of protein shape
Function:
help strengthen cytoskeleton
stabilize cell
Intermediate filaments
pair of hollow cylinders located near nucleus; each centriole consists of 9 microtubule triplets (9x3 structure)
Function:
mitotic spindle forms between centrioles during animal cell division many anchor and organize microtubule information in animal cells
absent in most plants
Centrioles
relatively short projections extending cells from the surface of a cell.
covered by a plasma membrane made of two central and nine pairs of peripheral microtubules (9+2 structure).
Function:
movement of some single-cell organisms.
used to move materials on the surface of some tissues.
Cilia
meaning of Prokaryote
“before the nucleus”
meaning of Eukaryotes
“True nucleus”
eukaryotic cell has three basic parts
the plasma membrane or cell membrane, cytoplasm
