biology review Flashcards
prokaryotic cells
oldest cell type
-small and simple
-lack nucleus
-lack membrane -bound organelles
-single celled
-single circular chromosomes (DNA) and multiple small simple plasmids(genetic material)
-simple cytoskeleton
-Prokaryotic organisms are unicellular
-The plasma membrane is surrounded by an outer cell wall.
-Many prokaryotes have flagella to enable them to move.
eukaryotic cells
-Eukaryotic cells are relatively large and more complex
-They have membrane-bound organelles such as a nucleus and mitochondria
-multicellular or single celled
multiple linear chromosomes (DNA)
-not all have a cell wall only plants and fungi
-complex cytoskeleton
Cytosol
is the aqueous fluid (dissolved salts and nutrients) that surrounds the organelles inside the cell
Cytoplasm
The liquid (dissolved substances) around the organelles is called the cytosol
-Moves materials throughout the cell
-Cytoplasmic streaming: The movement of the fluid substance
Plasma Membrane
-Outer boundary of cell
-Protects the cell
-Composed of lipid molecules that are interspersed with tiny protein channels.
-Controls what enters and leaves the cell.
Cell Wall
-Only found in plant cells
-Adds protection and support
-Made of cellulose - a complex carbohydrate
-Allows water and dissolved substances to pass through
Mitochondria
=Energy producers
-Site of cellular respiration- series of chemical reactions to make energy (ATP)
-Many mitochondria in muscle cells
ribosomes
-Makes proteins in the cell
-May be free in cytoplasm or attached to endoplasmic reticulum (ER)
-All cells must produce protein
Nucleus
-Controls most activities in the cell
-Contains all genetic information in the form of Deoxyribonucleic acid (DNA)
Endoplasmic Reticulum
-Series of folded membranes that form sacs or tubes
-Rough ER has ribosomes attached
-Proteins made by the ribosomes are packaged and transported by the ER
-Smooth ER has no ribosomes attached.
-Smooth ER synthesises lipids and assists in manufacturing of plasma membrane
Golgi Bodies
-Also called Golgi apparatus or Golgi complex
used for storing/ packaging and modifies protein
-Cells that make saliva or mucus have many Golgi bodies
-Site of modification, sorting, and secretion of lipids and proteins
Lysosomes
-Formed by the Golgi bodies
-Contain digestive enzymes to digest unwanted particles
-Help white blood cells to destroy bacteria
-Sometimes lysosomes may destroy the entire cell. Lysosome membrane ruptures, releasing enzymes, which then digest the contents of the cell: apoptosis (cell suicide).
-break down non-functional organelles
Plastids
-Organelles that contain coloured pigments
Chloroplasts
-Only found in plants/ algae
-Contain the pigment chlorophyll
Carry out the process called photosynthesis
Vacuoles
-Store food, water, or waste materials
-Plant cells have large vacuoles
-Vacuoles are able to expand, taking up 50-90% of the volume of the cell.
cell theory
-All organisms are composed of cells (and cell products)
-All cells come from pre-existing cells
-The cell is the smallest living organisational unit
All living things share the following attributes, remembered through the acronym MRS GREND.
M — movement: have some level of self-powered movement
R — respiration: the conversion of carbohydrates to a usable energy form (ATP)
S — sensitivity to stimuli: the response of an organism to its environment (e.g. plants responding to light, animals responding to external temperatures by sweating, shivering)
G — growth: an irreversible change in mass
R — reproduction: production of offspring, passing attributes from one generation to the next
E — excretion of wastes: produce wastes, such as dead cells or urine, that need to be removed
N — nutrition: intake of food or nutrients
D — DNA: the molecule that codes for the production of proteins
what makes a plant cell different
-have a cell wall
-big vacuole
-contains plastids
what makes a animal cell different
-lack cell wall
-small vacuoles
nucleolus
-found inside the nuclease
-functions to produce and assemble cell ribosomes
Peroxisome
Site where hydrogen peroxide and other harmful molecules are broken down
Diffusion
A net movement of substances travelling down its concentration gradient
-high concentration to low concentration
Simple diffusion
When molecules directly go through the cell membrane phospholipid bilayer they are usually small molecules or nonpolar eg carbon dioxide and oxygen passive transport=no energy
passive transport
Input energy is not needed (ATP)
Facilitated diffusion
Transport protein(carrier and channel proteins) helps molecules that are too big or polar to pass through,eg glucose
Cholesterol
Stabilizes membrane what keeps structure so not over crowded or far away making it better at what what passes through it
Protein channels (integral)
Help transport material through the cell membrane especially when they have a hard time passing through
Peripheral proteins:
Act at enzymes speed up reactions attracting cytoskeleton structure to help with cell shape
Osmotic pressure:
Pressure created by water moving across the membrane due to osmosis
More water moving=higher osmotic pressure
Things that affect the rate of diffusion
-distance the greater distance need to be travelled the slower diffusion rate
- higher temp more movement of molecules therefore diffusion faster
- particle size smaller particles faster rate of diffusion
Osmosis
Movement of water through a semipermeable membrane(high concentration to low )
Water molecules can travel through cell membrane or through protein channels in larger quantities
Low water= high solute concentration(eg sugar)
-water loves to move towards solute
hypertonic
Hypotonic
-higher solute(sugar, salt) concentration, less water
-lower solute concentration, more water
Active transport
Opposite of diffusion goes against concentration gradient so low to high concentration atp is needed
plasma membrane
-Outer boundary of cell
-Protects the cell
-Composed of lipid molecules that are interspersed with tiny protein channels.
-Controls what enters and leaves the cell.
phospholipids heads:
phospholipids tail:
Hydrophilic (water-loving) — dissolve in water. These are often lipophobic.
Hydrophobic (water-fearing) — dissolve in lipids (lipophilic).
what is asexual reproduction
it requires one organism to make more (children)
- they are genetically identical(clones), have no genetic variety
asexual reproduction pro and con
-efficient and fast since it involves one organism
-population could be wiped out in unfavourable environment as they are all vulnerable to the same conditions due to genetics
sexual reproduction involves…
the uniting of gamete(reproductive cell) to make new organisms
-genetically diverse as they are receiving from two diff. parents
binary fission process and what it occurs in
this process only occurs in prokaryotes
1. has to grow
2.replicate all genetic material (DNA, Plasmids)
3.starts to grow new cell when complete they pull apart
what would happen if the cell cycle was not regulated
cells can divide without order and accumulate genetic errors that can lead to a cancerous tumour
interphase
- DNA replicates
-centrioles become visible
prophase
-chromatin condenses
- centrioles move to poles of cell and start to project spindle fibres
-nuclear membrane breakdown
metaphase
-spindle fibres attach to chromosomes
- chromosomes line up in the centre of the cell
anaphase
- spindle fibres contract
- sister chromatids pulled apart
telophase
- new nuclear membrane forms
-chromosomes de-condense
purpose of metaphase checkpoint
to ensure that that all the chromosomes are aligned at the spindle equator before anaphase is initiated.
what happens in G1
cell undergoes growth increasing amount of cytosol. it also synthesis proteins that are needed for DNA replication
what happens in G2
further growth in preparation for cell division, DNA duplicated
what happens in S
the parent cell synthesises or replicated DNA by the end it has two identical copies of its original DNA
what happens in M
mitosis and cytokinesis
- spindle fibres have formed and chromosomes have lined up in the right position
- division of cel
two features describing stem cells
A) self renewal
ability to divide while maintaining unspecialised state
B)potency
ability to differentiate and transform into specialised cells
totipotency
most powerful potency found in zygote
pluripotency
any cell expect embryonic cell found in placenta
multipotent
rise to limited number of cells found in bone marrow
The two mechanisms by which apoptosis can be achieved are:
The two mechanisms by which apoptosis can be achieved are:
an intrinsic (internal) signal within the cell.
This is also known as the mitochondrial pathway. The intrinsic pathway is used when cells come under stress, such as through infection or damage. When cells are damaged during the cell cycle and the damage cannot be repaired, they undergo apoptosis via the intrinsic pathway.
an extrinsic (external) signal, where the signal is from a source external to the cell.
This is also known as the death receptor pathway. One way this may be generated is by a signal from the immune system.
cellular malfunctions (cancer):
breakdown of normal cells is mutated cell= uncontrollable growth
shoot system
shoot system the above-ground system of plants, the site of photosynthesis, transport of sugars and the site of reproductive organs
Root system
Root system the below-ground system of plants which anchors the plant in the soil, is responsible for the absorption and conduction of water and minerals, and the storage of excess sugars (starch)
permanent tissue
-no cell division
-already formed specific cell/specialised
meristematic tissue
-always growing/dividing
types of permanent tissue
dermal tissue:
-“skin”
-epidermal
-green —>chlorophyll
—>traps sunlight
ground tissue:
-roots, H2O uptake
vascular tissue:
transport of water and nutrients
types of meristematic tissue
stem cells; undifferentiated cells that become other cells
Ground tissue components
parenchyma tissue — In leaves, the parenchyma tissue is the site of photosynthesis. In roots, tubers and seeds, the parenchyma tissue is the site of storage of starch
collenchyma—thick, flexible walled cells in plants; the main supporting tissue of stems
sclerenchyma —dead cells with thickened walls for strength and rigidity
vascular tissue components
xylem:
-H2O and minerals transport
-includes tracheid and vessals
Phloem:
-nutrient transport
-glucose for photosynthesis
Tracheids and vessels
Tracheids are present in all vascular plants and are long and tubular, whereas vessels are only present in flowering plants and have a wide pipe-like structure
Plant tissues involved in the intake of water
Uptake of water by plants occurs through osmosis by the root hairs.
Root hairs are extensions of cells of the epidermal tissue that forms the outer cellular covering of the root.
Stomata
The stomata are the sites of carbon dioxide uptake and loss of water in a plant.
Stomata are mainly located in the lower epidermis of leaves.
Water is lost as vapour when a concentration gradient exists between the water content in the leaf spaces (high) and in the air outside the leaf (low) and the leaf stomata are open
digestive system: Mouth
mechanical digestion: physical breakdown of food smaller pieces done by teeth and tounge
Chemical digestion (Break chemical bonds in food ):
*Lubrication of food
* Enzymes -(salivary amalayase )
* break down carbohydrate
digestive system: oesophagus
- Moves food from the throat to the stomach → Muscle movement called peristalsis
- If acid from the stomach moves back into the oesophagus=heartburn
digestive system: stomach
*muscular organ which further churns food ,forming chyme mush(mechanical digestion)and mixes it with pepsin(enzyme that begins chemical digestion of protein)
digestive system: small intestine
*the small intestine produces intestinal juice which contains amylase(starch to breakdown) protase and lipase(digests fats to fatty acid)
FUNCTION: digestion and absorption of food occurs here
*nutrients from the food pass into blood stream (carbohydrates and protein)
→villi and microvilli increase SA to help with absorption
digestive system:liver
filtration of the blood coming from from the intestine before it is passed down to the rest of the body.
* Filters out toxins and waste. Detoxifies poisonous substances
digestive system: Gall bladder
BILE Is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps w/ digestion. It breaks down fats into Fatty acids, Bile contains: Mostly cholesterol
digestive system: pancreas
- produce compounds to digest fats and proteins
- regulates blood sugar by producing insulin
digestive system: large intestine
absorption of water and storage of the remainder of the waste material
endocrine system:
endocrine system is a network of endocrine glands that deliver chemical messages (hormones) in the blood stream to target tissues.
endocrine glands: produce hormones.
→ Unlike exocrine glands which produce enzymes, sweat, tears endocrine glands are ductless and secrete, their hormones direly into the bloodstream.
endocrine system: hormones
A chemical messenger (signalling molecule) which targets a group of cells in order to cause that group of cells do some activity or stop doing an activity
endocrine system: hypothalamus
→ controls the endocrine system
endocrine system: pituitary(gland)
secretes a diff. hormones:
- Growth
- Blood pressure
- Metabolism
endocrine system: thyroid (located in the neck)
→ regulates rates of metabolism in the body
endocrine system: parathyroid
→ control metabolism of calcium
endocrine system: Adrenal glands(located at the top of each kidney)
→ Hormones released are cortisone and adrenaline
* function of cortisone: regulate carbohydrate, protein, and fat metabolism
* function of adrenaline: raise blood sugar levels and increase heartbeat and breathing rates
excretory system
the excretory system is responsible for removing metabolic and other wastes (excess, unnecessary or dangerous materials)from the blood and plays a role in water balance.maintaining homeostasis or internal environmental balance
The Excretory system in consists of organs (skin, the liver, the lungs and the kidney) which are responsible for the elimination of metabolic wastes
what are the Harmful wastes, Nitrogenous wastes such as(n-waste)
ammonia and urea from the metabolism of protein
creatine and creatinine from the metabolic activities of skeletal muscle.
Nephrons purpose
Goal is to process waste products from the blood to create urine (functional unit of a kidney)
Glomerular filtration includes
Glomerular filtration:
Blood pressure forces fluid from the blood in the glomerulus into the bowman’s capsule
The filtrate contains a mixture of glucose, salts, vitamins, nitrogenous wastes and other small molecules
Tubular reabsorption includes
Reabsorption is the process by which water and useful solutes are removed from the filtrate and returned to the blood. The major site of reabsorption is the proximal tubule
When the filtrate exits the glomerulus, it flows into a duct in the nephron called the renal tubule. As it moves, the needed substances and some water are reabsorbed through the tube wall into adjacent capillaries.
move by simple diffusion, facilitated diffusion or active transport(require atp) from the tubule into the surrounding capillaries.
All nutrients, such as glucose and amino acids, and most of the water and inorganic ions, such as sodium, potassium, phosphate and calcium are reabsorbed across the wall of the proximal tubule and enter the peritubular capillaries of the blood stream
Tubular secretion:
Tubular secretion:
Secretion is the process of transporting specific compounds, typically waste products, out of the blood of the peritubular capillaries into the tubular filtrate that will eventually become urine. Secretion occurs mainly in the proximal tubule, but some also occurs in other regions of the tubules
Secretion occurs mainly by active transport, but some also occurs by passive diffusion
glomerulus
filters small solutes from the blood
proximal convoluted tubule
reabsorbs ions, water and nutrient removes toxins and adjusts filtrate pH
distal tubule
selectively secretes and absorbs different ions to maintain blood PH balance
collecting duct
A reabsorbs solutes and water from the filtrate
loop of henle
Its main function is to reabsorb water and sodium chloride from the filtrate. This conserves water for the organism, producing highly concentrated urine.
Negative Feedback:
A negative feedback loop is a process in which the body senses a change in a variable and activates mechanisms to reverse the change. Negative feedback is a key component of homeostatic control loops that regulate many body variables and maintain the body’s internal conditions within narrow limits.
a stimulus response mechanism where a change in a variable is detected (the stimulus) and a response occurs which reverses the direction of change, bringing the variable back within normal range.
osmoregulation
The process by which an organism regulates the water balance in its body and maintains the homeostasis of the body is called osmoregulation. Osmoregulation is the maintenance of a constant osmotic pressure of the body fluids within a normal range
Controlling water balance is important to ensure the cells of the body are in equilibrium
Too much water outside cells and the cells will absorb it, possibly lysing(the breakdown of a cell caused by damage to its plasma (outer) membrane.)
Too little water inside cells and the cells will release water, possibly collapsing
What is the renal artery afferent and efferent arteriole?
Afferent arterioles deliver blood to the glomerulus, and efferent arterioles carry blood away from the glomerulus.
Afferent: approaching nephron=high oxygen, lower carbon dioxide, high urea, unbalanced ions and water
Efferent: leaving nephron=lower oxygen, higher carbon dioxide, lower urea, balanced ions and water.
3 major n-waste excreted, Advantage and
Disadvantage
N waste
Advantage
Disadvantage
Ammonia
Less energy to produce
Highly toxic requires a lot of water
Urea
Moderate energy required to produce
Still requires water for excretion, so water loss still an issue
Uric acid
Very little water required, low toxicity
High energy cost for production
how does the structure of a proximal tube aid its function
Reabsorption from the proximal tubule to the blood is enhanced by the presence of microvilli on the epithelium
that greatly increase the surface area available for reabsorption
How Feature assists osmoregulation:
Long and short proximal convoluted tubule
Long proximal convoluted tubule: increases water reabsorption
Found in marine fish
Greater surface area for reabsorption to occur
Short proximal convoluted tubule: decreases water reabsorption
Found in freshwater fish
Less surface area for reabsorption to occur
How Feature assists osmoregulation:
Small or large glomeruli & bowman’s capsule
Small glomeruli & bowman’s capsule: reduces filtration rate
Found in saltwater fish
Less volume of filtrate
Saltwater fish lose toxic ammonia over gills, the kidney is not required to filter N-waste form blood
Minimise water loss in urine
Large glomeruli & Bowman’s capsule increase filtration rate: maximise filtration rate
Greater volume of filtrate, increase water loss in urine
How Feature assists osmoregulation:
Large or small loop of Henle
Large loop of Henle: increases water & ion reabsorption
Found in terrestrial organisms that live in dry environments and need to conserve water
Increases water reabsorption
Minimise water loss in urine
Excrete highly concentrated urine
Small loop of Henle: reduces water & ion reabsorption.
Found in organisms that live in moist environments
Less water reabsorption
less concentrated urine excreted
How Feature assists osmoregulation:
degree of Vascularization(the number of blood vessels in a tissue)
Heavy vascularisation = large surface area for rapid reabsorption of water and solutes back into the bloodstream
= more reabsorption
Light vascularisation = small surface area, decrease reabsorption of water back into the bloodstream
The rate of transpiration is affected by environmental factors:
The rate of transpiration is affected by environmental factors:
humidity: the greater the content of water vapour in the air, the lower the rate, such that at 100 per cent humidity in the air, net water loss by transpiration stops
wind speed: transpiration is least in still air and, all other things being equal, increases as wind speed increases, as moving air removes water vapour from around the leaves
temperature: as temperatures increase, the rate of evaporation of water increases
light intensity: light stimulates the opening of the leaf pores (stomata).
humidity: the greater the content of water vapour in the air, the lower the rate, such that at 100 per cent humidity in the air, net water loss by transpiration stops
wind speed: transpiration is least in still air and, all other things being equal, increases as wind speed increases, as moving air removes water vapour from around the leaves
temperature: as temperatures increase, the rate of evaporation of water increases
light intensity: light stimulates the opening of the leaf pores (stomata).
Hypertonic
High solute low water
