unit 1 and 2 bio theory

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:

1. self renewal: the ability to go through several cell cycles without further differentiation

2. 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

1. cells are the basic unit of life

2. all organisms are composed of cells

3. 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