BIOLOGY UNIT 1/2

plasma membrane

a phospholipid bilayer that encloses the contents of a cell, and controls the passage of substances into and out of the cell

phospholipid head

hydrophilic

fatty acid tail

hydrophobic

why is it a fluid mosaic

it is made up of lipids and protein that are side by side which allows it to flow

transmembrane proteins

proteins that provide a pathway from one side of the membrane to the other

diffusion

the passive net movement of a substance from a region of high concentration to a low concentration

simple diffusion

the diffusion of solutes across a plasma membrane

what molecules can enter via simple diffusion

small and non-polar

osmosis

the passive net movement of free water molecules through a semi-permeable membrane, from a region of low solute to a region of high solute concentration

isotonic

of a solution, having the same osmotic pressure as the cytoplasm

hypertonic

of a solution, having a higher osmolarity than the cytoplasm

hypotonic

of a solution, having a lower osmolarity than the cytoplasm

facilitated diffusion

the passive movement of molecules across a biological membrane via specific transmembrane integral proteins

what molecules move through facilitated diffusion (protein channels)

small, polar molecules and ions

what are protein channels used for

facilitated diffusion

what are gated channel proteins

protein channels used for facilitated diffusion that only open to certain stimuli

carrier protein

change shape to enable large, polar or charged molecules (glucose and amino acids) through

what is active transport

The active movement of molecules against their concentration gradient, across a membrane via specific transmembrane integral proteins.

exocytosis

Bulk transport of molecules out of a cell.

bulk transport

Active movement of a large molecule into or out of a cell, by enclosing it in a membrane sac.

Endocytosis

Bulk transport into a cell from the extracellular fluid.

Phagocytosis

Endocytosis of solid material, such as bacteria

pinocytosis

endocytosis of fluid material, such as lipids

which direction does DNA polymerase III run

3’-5’

binary fission

most prokaryote cell reproduce by splitting into two daughter cells

Origin of replication

The point on a circular chromosome at which the protein DnaA accumulates, stimulating the assembly of a replisome

first step of binary fission

the circular DNA is replicated

step two of binary fission

the chromosomes attach themselves to the cell membrane at the ends

step three of binary fission

the cell elongates

step four of binary fission

a z-ring forms in the middle of the bacteria

step five of binary fission

the z-ring constricts the cell, pinching it in at the middle

step six of binary fission

a new cell wall begins to form called a septum in the middle of the cell

final step of binary fission

the septum is divided, resulting in two daughter cells

purpose of cell division

growth and repair of tissues

interphase phases

G1, S and G2

early prophase

the nucleolus disappears and the chromatin starts to condense and become visible

prophase

the nuclear membrane breaks down and the centrioles move to the poles of the cell

late prophase

the chromosomes are fully visible and the spindle is complete

metaphase

nuclear membrane is gone and the chromosomes line up in the centre

anaphase

the spindle fibres shorten and the chromatids are pulled to the opposite poles

late anaphase

the chromosomes reach the poles of cell and the spindle fibres begin to disappear

telophase

the chromosomes decondense and the nuclear membrane reforms. The cell pinches in the middle

cytokinesis

the cell has fully split

Apoptosis

the natural and controlled death of cells within our body

Purpose of apoptosis

to remove unwanted cells without causing stress or damage to neighbouring cells

Pathways of apoptosis

mitochondrial pathway (intrinsic)

death receptor (extrinsic)

extrinsic pathway

involves transmembrane death receptors that are members of the tumour necrosis receptor gene family. they bind to extrinsic lignands and transduce intracellular signals that result in cell destruction

lignands

molecules that are larger than itself

intrinsic pathway

starts within the cell and is activated in response to signals resulting in DNA damage, loss of cell survival or other types of cell stress. Pro-apoptotic proteins are released from he mitochondria

caspases

a group of enzymes involved in cell death

function of caspases

they cut or cleave other proteins at a certain point

caspase cascade

Process of programmed cell death where a series of proteases, called caspases, are activated and cleave specific cellular proteins leading to cell death.

P53 gene

a tumour suppressor gene that stops the cell cycle if there is damage in a cell until the damage is repaired. If the damage cannot be repaired, apoptosis occurs.

mutated p53

the cell cycle continues and the cells can become cancerous

point mutation

one amino acid where a mutation occurs

Alzheimer’s disease

a slowly progressive disease of the brain that is characterised by the impairment of memory and eventually disturbances in planning, language and perceptions

cell differentiation

the process where cells become specialised for a specific function

gene expression in humans

determines what cell type will develop from a totipotent embryonic cells

stem cells

undifferentiated cells that can become anything the body needs. They divide to produce daughter cells that can either continue to be stem cells or differentiate into specialised cells

three main functions of stem cells

reproduce themselves for long periods

be undifferentiated

produce differentiated cells

embryonic stem cells

ESC may be obtained from the inner cell mass of an embryo at the early blastocyst stage. These cells can use almost any part of their genetic material which means they can become almost any specialised cell

endoderm

the innermost germ layer

what can the endoderm differentiate into

most of the digestive tract, thyroid, lungs and bladder

Mesoderm

the middle germ layer

what can the mesoderm differentiate into

muscles, heart, blood vessels, inner skin layer and skeleton

ectoderm

the outermost germ layer

what can the ectoderm differentiate into

nervous system, hair, sweat glands, nails, tooth enamel, lens of the eye

red blood cell

erythrocyte

phagocytic white blood cell

neutrophil

hematopoiesis

describes the production of blood cells

totipotent

these cells have the potential to give rise to all cell types

pluripotent

these are the cells of the primary germ layers: ectoderm, mesoderm and endoderm. These cells differentiate into many cell types.

Multipotent

these cells have the ability to differentiate into a closely related family of cells; for example, a multipotent blood stem cell can develop red blood cells, white blood cells or platelets

Oligopotent

these cells have the ability to differentiate into a few cell types such as adult somatic stem cells

Unipotent

these cells have the ability to produce only cells of their own type, but because they can self-renew they are termed stem cells

guard cells

specialised plant cells in the epidermis of leaves, stems and other organs that are used to control gas exchange

stomata

a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange

root hairs

each of a large number of elongated microscopic outgrowths from the outer layer of cells in a root, absorbing moisture and nutrients from the soil

xylem

the vascular tissue in plants which conducts water and dissolved nutrients upwards from the root and also helps to form the woody element in the stem.

phloem

the vascular tissue in plants which conducts sugars and other metabolic products downwards from the leaves.

types of vascular plant tissue

meristematic and permanent tissue

meristematic tissue

continues to undergo cell division such as roots

permanent tissue types

dermal, ground, vascular

ground tissue types

parenchyma, collenchyma, sclerenchyma

tracheids

Specialized plant cells that transport water and minerals through pits in their thick cell walls. Found in xylem tissue and are elongated with tapered ends.

photosynthesis word equation

carbon dioxide + water →(light + chlorophyll) glucose + oxygen

photosynthesis chemical equation

6CO2 + 6H2O →(light + chlorophyll) C6H12O6 +6O2

thylakoid

where photosynthesis begins

grana

stack of thylakoid

stroma

part where energy gets sent through

light dependent stage of photosynthesis

occurs within the thylakoid where solar energy gets converted to chemical

light dependent input and output

H2O, ADP, Pi, NADP+, light → O2, ATP, NADPH

what do high energy electrons produce?

NADPH and ATP

Calvin cycle (light independent reaction)

occurs within the stroma

Calvin cycle input and output

carbon dioxide, ATP, NADPH→ glucose, ADP, NADP+, Pi, 6water

what are formed during the calvin cycle

sugar (glucose)

cellular respiration word equation

glucose + oyxgen → carbon dioxide + water + energy