revise for semester exam!
chemical energy is…
energy stored in bonds of chemical compounds (atoms/molecules)
needed to join chemical compounds together
if molecules are broken apart, energy is released
ALL CELLS require energy for:
growth
reproduction
repair
how do plants obtain glucose?
through photosynthesis
autotrophs
are PRODUCERS
they create their own food using inorganic material (light, water, carbon dioxide) through photosynthesis or chemosynthesis
how do animals obtain glucose?
eating
heterotrophs
are CONSUMERS
eat other organisms (plants/animals) to get energy and nutrients
which organisms are autotrophs?
algae
plants
plankton
bacteria (autotroph and heterotroph)
which organisms are heterotrophs?
bacteria
protists
fungi
yeast
animals
how do organisms turn glucose to energy?
through CELLULAR RESPIRATION
not breathing!
breaks up glucose into ATP
cellular respiration is the … of photosynthesis
reverse
cellular respiration equation
what is Chemosynthesis?
involves the use of energy released by inorganic chemical reactions to produce food.
how is ATP made (in cellular respiration?)
cells break apart glucose molecules, which is then used as energy
how does ATP work?
an ATP molecule releases energy when a phosphate bond is broken
it then becomes ADP (adenosine diphosphate) + “free” phosphate
this can be “recharged” to form ATP, and then used again
the THREE stages of cellular respiration are:
glycolysis
Krebs cycle
electron transport chain
glycosis is…
the breakdown of glucose
1 glucose molecule → 2 pyruvate molecules, 2 NADH and 2 ATP molecules
occurs in the cytoplasm of the cell
anaerobic
anaerobic meaning
doesn’t require oxygen
if oxygen is/isn’t avaliable for glycosis…
IS:
the Krebs cycle and the electron transport chain take place
the 2 pryuvate molecules go to the Krebs cycle
2 NADH molecules go to the electron transport chain
ISN’T:
fermentation will occur
Krebs cycle…
occurs in the MATRIX (of mitochondria)
pryuvate is converted to Acetyl-CoA, then to Citric Acid
this is then broken down into CO2 and H + 2 ATP molecules, plus some NADH
electron transport chain…
occurs in the cristae (mitochondria)
NADH/FADH give up their H atoms, which combine with O2 to form H2O
this releases enough energy to produce 32/34 ATP molecules
electron transport chain FORMULA
what if there is NO oxygen for the electron transport chain?
FERMENTATION occurs
in animals: lactic acid is produced
in plants and micro-organisms, alcohol and carbon dioxide are produced
doesn’t produce additional ATP, but prevents accumulation of pyruvate and allows glycolysis to continue
fermentation
an anaerobic process in which energy can be released from glucose even though oxygen is not available
will not go through citric acid cycle and electron transport chain system
glycolysis continues to occur, where small amounts of ATP is made
what are stem cells?
a single cell that can replicate itself or differentiate into many cell types (under special conditions)
how do stem cells differentiate into other cells?
they activate any part of their DNA material
normal specialised cells “switch off” the genes that they don’t need (e.g. muscle to skin cell)
all stem cells have two main properties:
self renewal: the ability to go through several cell cycles without further differentiation
potency: the ability to differentiate (change) into specialised cell types
pluripotent stem cells
a stem cell that can differentiate into any cell type within a broad group
embryonic stem cell
an undifferentiated, totipotent or pluripotent cell found in the early embryo.
totipotent stem cell
an undifferentiated cell that can later differentiate into any type of cell
multipotent stem cell
a stem cell that can differentiate into a limited number of closely related cell types
oligopotent stem cell
a stem cell that can only differentiate into a few cell types
unipotent stem cell
can only form one cell type on division
stem cells in animals
the first mass of cells develop into a blastula
as further division occurs, the mass begins to push into the cavity of the embryo, forming the gastrula
when this happens, the first stage of cell differentiation is triggered
how do cells form their specialised type?
depending on where the cell is in the gastrula, it will receive a chemical message to switch on or off the DNA of specific genes
this will provide specific instructions on what shape to take and what functions to perform (e.g. the skin may become muscle, gut or skin cells).
adult stem cells
responsible for the repair and maintenance of the adult body
permeable
allowing liquids or gases to pass through it
blastula
a hollow ball of cells resulting from division in the animal zygote
gastrula
the early embryonic stage in the animal formed from the ingrowth of cells at one end of the blastula to produce a double layer of cells (from which future tissues and organs develop)
apical meristem
the growing point of the tip of the root and stem in vascular plants
cambium
the layer of actively dividing plant cells
cellular needs:
input of nutrients - oxygen
removal of waste - carbon dioxide
factors affecting the efficiency of diffusion
surface area of diffusion surface
distance which molecules in concentration gradient must travel
level of concentration gradient
the type of gas exchange system employed is determined by:
organism size
environmental medium
specialised surfaces that increase the surface area available for gas exchange:
thin
flat
moist cells
neighbouring blood supply
disadvantages of living in water
oxygen not very soluble in water - 1% compound to 21% in air
water is very viscous - does not flow easily - this limits the flow of water across gas exchange surfaces to one direction - too much energy for both ways
disadvantages of living on land
drying effect of air
lack of support: effect of gravity much higher
gills
are several paired arches lying on each side of the buccal cavity (mouth)
Protected from external environment by a operculum
From each gill arch extends two rows of gill filaments that spread out
Filaments further subdivided to increase surface area – up to 10 times the surface area of the fish
Constant stream of water flows over – maintaining the concentration gradient
gills - countercurrent
significantly increases the efficiency of gas exchange system - Ensures the concentration gradient is always high
bronchus
division of trachea leading to lung; cartilaginous rings prevent collapse
bronchiole
formed from branching of the bronchus; has no cartilaginous rings in terminal branches
alveolus
the actual site of gas exchange between the air and blood.
single layer of cells separates the air from the blood capillary
diaphragm
domed, muscluar structure separating the thorax from the abdominal cavity.
contraction and relaxation change the volume of the throat
intercostal muscles
move the ribs and thus change the volume of the thoracic cavity
sternum
breastbone, attached to the ends of each pair of ribs. ribcage acts as a single unit
pleural membranes
surround the lungs and line the thoracic cavity
expiration (ventilation)
breathing out
inspiration (ventilation)
breathing in
the absorption of nutrients (at the cell membrane) involves:
osmosis
diffusion
active transport
the diffusion of nutrients depends on:
the concentration gradient and the length of the diffusion pathway
the ileum
helps to further digest food coming from the stomach and other parts of the small intestine.
villi
finger-like proteins that increase the surface area for digestion and absorption
microvilli
their presence increases the surface area of villi
are hair-like extensions on the epithelia cells of the villi
absorption of lipids (fats): PROCESS
small droplets of lipids + their subunits (glycerol and fatty acids) are absorbed into the villi’s epithelial cells
here they are:
assembled into fat storage molecules, phospholipids and cholesterol
packaged in a protein coat by the cells’ Golgi bodies into chylomicrons (structures)
chylomicrons are released into the tissue fluid and taken up by the lacteals (of lymphatic system) in the villi
lacteals lead to lymphatic vessels which enter the blood supply
where are vitamins, inorganic salts and water absorbed?
in the small intestine
(absorption of water occurs due to osmosis as gut contents develop a lower solute concentration (hypertonic) compared to the blood
results in the compaction of insoluble, indigestible materials (faeces)
if the material passes through the digestive system too quickly…
less water is removed, causing diarrhea
if the material passes through the digestive system too slowly…
an excess of water is removed, resulting in constipation
Chrohns disease
A chronic inflammatory disease, primarily involving the ileum and large intestine
Can result in:
Intestinal obstruction due to the thickening of intestinal walls
Malnutrition
assimilation
the incorporation of simple organic molecules, or products of digestion into complex constituents of the organism
oxygen
essential component in life
role in breathing processes
appropriate levels required to support cellular respiration (which produces energy in cells)
(nutrient) water
essential component of body cells
makes up 2/3 of body
required to dissolve other chemicals (so they can be transported through the body)
also used as a reactant in many reactions
(nutrient) lipids
includes fats and oils
stored under the skin as an energy reserve and an insulator
stores important fat-soluble vitamins
used for making cell membranes and nerve cells
(nutrient) carbohydrates
main source of energy for the body
includes starches and sugars
broken down to glucose in the body and transported to cells to be used in cellular respiration
excess glucose converted to body fat and stored
(nutrient) proteins
required to build new cells and maintain tissues
required for growth and repair of damaged and worn tissues
essential for synthesising specialised proteins in the body to perform basic bodily functions
(nutrient) vitamins
required in small amounts to:
speed up various chemical reactions in the body
maintain good health
(nutrient) minerals
elements or other chemically simple substances that are required for:
healthy growth
to avoid deficiency diseases
what are some diseases that can be caused from a deficiency of vitamins A, B, C and D?
vitamin A: night blindness
vitamin B: anaemia
vitamin C: scurvy
vitamin D: rickets
what are the two types of membrane proteins?
integral and peripheral
cells
the basic unit of life
tissues
clusters of cells performing a similar function
organs
made of tissues that perform one specific function
organ systems
groups of organs that perform a specific purpose in the human body
organism
the entirety of organ systems working together in a highly structured and coordinated fashion
the 11 human body systems
nervous system
respiratory system
integumentary system
digestive system
excretory system
skeletal system
muscular system
circulatory system
endocrine system
reproductive system
lymphatic (immune) system
principles of cell theory
cells are the basic unit of life
all organisms are composed of cells
all cells arise from preexisting cells
types of cells
prokaryotic
eukaryotic
characteristics of all cells
surrounding membrane
protoplasm - cell contents in thick fluid
organelles - structures for cell function
control center with DNA
prokaryotic cells
molecules surrounded by membrane and cell wall
no membrane bound nucleus
nucleiod = region of DNA concentration
organelles not bound by membranes
eukaryotic cells
nucleus bound by membrane
include fungi, protists, plant and animal cells
possess many organelles
ATP (adenosine triphosphate)
the principal molecule for storing and transferring energy in cells
organelles
A small structure in a cell that is surrounded by a membrane and has a specific function.
cell walls
found in plants, fungi and many protists
surrounds plasma membrane
NOT in animal cells
cytoplasm
viscous fluid that fills the cell and contains organelles
components of a cytoplasm
interconnected filaments and fibers
fluid = cytosol
organelles (not nucleus)
storage substances
function of cytoplasm
contains molecules such as enzymes which break down waste and aid in metabolic activity
responsible for cell shape - cytoskeleton
cytoskeleton
filaments and fibers
made of 3 fiber types
microfilaments
microtubules
intermediate filaments
the 3 functions of a cytoskeleton
mechanical support
anchor organelles
help move substances
microfilaments
fine strands of globular protein actin
bind with other proteins to hold organelles in place
interactions with another protein will bring about movement of the cytoplasm and the cell as a whole
microtubules
hollow cylinders of protein tubulin
provide greater mechanical support for the cell
provide routes for materials to move within the cytoplasm
form spindles during cell division
intermediate filaments
composed of a variety of fibrous proteins
strong, stable and resistant to stretching
provides mechanical support
cilia
short hair-like structures
provide motility
used to move substances outside human cells