Bio Sem 1 Rev Flashcards
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Why is homeostasis important
To maintain a balanced level of temp/blood sugar level or the cells of the body to function
Define Homeostasis
The maintenance of a stable internal environment within the body despite changes in the external environment
Factors under homeostatic control
Temp - 36.5-37.5 C
pH - 7.35-7.45
Blood sugar levels
O2 CO2 concentration
Fluid balance
Stimulus
Change in the internal or external environment
Receptor
Structures that detect changes to the environment (usually cells)
Control Centre / Modulator
Cells / Organs (often the nervous system) that “decide” on a response
Effector
The molecule, cell or organ that produces a response
Response
Any change in the cell, organ or organism caused by the stimulus
Stimulus - Response Model (in order)
Stimulus –> Receptor –> Modulator –> Effector –> Response
Types of Receptors
Thermoreceptors
Nociceptors
Baroreceptors
Chemoreceptors
Photoreceptors
Define Thermoreceptors
Detects changes in Temperature
Define Nociceptors
Detects painful stimuli (skin)
Define Baroreceptors
Detects changes in pressure
Chemoreceptors
Detects changes in chemical concentration
Photoreceptors
Detects changes in light
Negative Feedback
The response acts to counteract the internal stimulus to return the body to the set point (homeostasis)
Positive Feedback
The response acts to increase the initial stimulus. (pushes the body away from a set point)
Hypothalamus
Structure deep in the brain responsible for monitoring and controlling your body temp
Thermoregulation - Two ways the body cools itself down
Sweating
Vasodilation
Vasodilation
Capillaries under the skin widen when you get hot, allowing more blood to circulate closer to the surface of the body
Thermoregulation - 3 things the body does to keep warm
Vasoconstriction
Piloerection
Shivering
Vasoconstriction
Capillaries under the skin shrink when you get cold, keeping the blood away from the surface of the body
Piloerection (Goosebumps)
Small muscles at the base of the hair follicles pull the hair so it stands up (traps heat)
How does SA:V affect heat loss and insulation?
Greater SA:V allows for easier heat loss
Lesser SA:V allows for insulation
Hypoglycemia
Low blood sugar level
Hyperglycemia
High blood sugar level
2 hormones from the pancreas that regulate blood glucose levels
Insulin
Glucagon
Glucose
Sugar molecule necessary for cellular resp and functioning of all cells
Glycogen
Stored form of glucose (cannot be used by cells)
Glucagon
A hormone that helps to raise glucose concentration in the blood
When is Glucagon released? And where is it released from?
Where: secreted from alpha cells
When: Secreted when blood sugar levels are low
How does glucagon help increase blood glucose levels?
Stimulates the liver to convert glycogen into glucose and release it into the blood
Insulin
Lowers blood glucose levels
When is insulin released and where is it released from?
Where: secreted from beta cells
When: secreted when blood sugar levels are high
How does insulin help lower blood glucose levels?
Stimulates liver to convert glucose from the blood into glycogen
Can target skeletal muscles and cells to take up more glucose
Islets of Langerhan
Pancreatic cell that produces hormones (Insulin and glucagon)
Type 1 diabetes
The immune system destroys the insulin-making cells in the pancreas
Type 2 diabetes
Body cells become resistant (no longer respond) to insulin
Phospholipid Structure
Hydrophilic head
Hydrophobic tails
Phospholipid Bilayer Structure
Heads point out tails hide in middle of the layer
Main components of the plasma membrane
- Phospholipids
- Cholesterol
- Proteins
Cholesterol
Scattered through phospholipid tails
Helps control the fluidity of the membrane
Transport proteins
Channel and carrier proteins assist the movement of substance through the cell membrane
Types of transport
Passive transport
Active transport
Types of passive transport
Osmosis (fluids)
Diffusion (high to low concentration gradient)
Facilitated Transport - Assisted (no energy
Types of active transport
Vesicles
Protein pumps
Active transport - protein pumps
Movement of molecules across the membrane, against the concentration gradient , requires energy, only occurs through carrier proteins
ATP - name
Adenosine triphosphate
Draw and Label the ADP -ATP cycle
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Bulk transport
Movement of molecules in and out of cell via vesicles (requires energy)
Vesicles
Small bubbles of phospholipids
MRSGREEN
Movement
Respiration
Sensitivity
Growth
Reproduction
Equilibrium
Excretion
Nutrition
Cell Theory
- All organisms are made of cells
- The cell is the most basic unit of life
- All existing cells are produced by other living cells
Types of cells
Prokaryotic
Eukaryotic
Prokaryotic
Cells without a nucleus or other membrane-bound organelles
Eukaryotic
Cells with a nucleus and membrane bound organelles
Cytoplasm/Cytosol
- Fluid-like substance inside the cell
- All cell organelles sit within the fluid and important chemical reactions take place here
Ribosome
- Non-membrane bound organelle
- Site of protein synthesis
- Found floating in cytoplasm or attached to Endoplasmic Reticulum
Cytoskeleton
Structure that helps cells maintain shape and internal organisation
Organelles only in Plant cells
Cell wall
Chloroplast
Nucleus
- the control centre of the cell
- contains the main gene material
- Surrounded by a membrane
Nucleolus
- a small dark region within the nucleus
- responsible for making ribosomes
Endoplasmic Reticulum
- Transport system in the cell
- Made of connected network of membranes and is found close to the nucleus
Golgi Body
Prepares and packages cellular products for export out of the cell
Vacuole
- Membrane-bound structure
- Stores important cellular materials (water, waste, sugars)
- plant cells have a large central vacuole
Lysosome
- Stomach of the cell
- contains digestive enzymes
- breaks down complex molecules
Mitochondria
- Site of cellular respiration
- Generates ATP
Centriole / Centrosome
- Structure that appears in animal cells when dividing
- Helps separate the chromosomes
Chloroplasts
Green in colour- double membrane containing green pigment chlorophyll which carries on photosynthesis
Photosynthesis chemical formula
6CO2 + 12H2O – light and chlorophyll–> C6H12O6 + 6O2 + 6H2O
Phases of photosynthesis
Phase One
Light-dependent phase (LDP): This occurs in the thylakoid/grana, the light energy is captured by the chlorophyll, which is used to split water molecules. The water molecules then release 2H+ and oxygen as well as energy. These products are used as waste and cell functions.
Waste = oxygen for us.
For the organelle = energy is used to charge ADP and energy with H+ is used NADP+ to NADPH.
Carrier molecules: ATP and NADPH get charged up by the light dependent reactions. ATP carry energy, NADPH carry H to the light independent reactions.
Phase Two:
Light-independent phase (LIP): Occurs in the stroma and doesn’t require the help of light. Only needs carbon dioxide from the atmosphere and the products of LDP. The products supply the energy and H to produce glucose from CO2. Then after the reaction is done, the used products (ATP and NADPH) turn into ADP and NADP+ to then cycle back to the LDP (Light dependent phase). Happens in Calvin Cycle.
Light Dependent Phase - Location, Inputs, Outputs
Location - Grana / Thylakoid
inputs - Light, Water, NADP+ and ADP
Outputs - Oxygen, NADPH and ATP
Light Independent Phase - Location, Inputs, Outputs
Location - Stroma
Inputs - Carbon dioxide, NADPH and ATP
Outputs - Glucose, NADP+ and ADP
Mutagen
changes in cell that causes Mutations
SA:V ratio and how it affects cells
Greater SA:V ratio means the cells export and import resources faster
Lesser SA:V ratio means the cells export and import resources slower
Difference between Autotroph and Heterotroph
Autotroph produces its own food
Heterotrophs cannot produce its own food and rely on other sources of food (autotrophs or other heterotrophs)
Equation for Aerobic cellular respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O
When does aerobic cellular respiration take place?
When oxygen is present
3 main stages of cellular respiration
Glycolysis
Kreb Cycle
Electron Transport Cycle
Glycolysis - Location, inputs, outputs
- Occurs in cytoplasm
- Input: glucose, ADP, NAD+
- Output: Pyruvate 2 ATP and NADH
Kreb Cycle
- occurs in mitochondrial matrix
- Input: pyruvate (acetyl COA), ADP, NAD+, FAD+
- Output: CO2, NADH, FADH2, 2 ATP
Electron Transport Cycle
- Occurs in the inner membrane
- input: NADH, FADH2, O2
- Output: H2O, 26 or 28 ATP, NAD+, FAD+
Anaerobic: No oxygen
- Makes 2 ATP + water
- Lactic acid or alcohol
Compare products of aerobic respiration with products of anaerobic respiration
Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by- products and ATP is energy that is transformed from the process.
Describe binary fission in prokaryotes
1 cell dividing into 2 identical daughter cells
Purpose of cell replication
- allows the body to renew itself
- repair damages
4 phases of the eukaryotic cell cycle
G1
S
G2
M-phase (Mitosis
G1
cell growth new copies of organelles are made
S
DNA replication
G2
growth and preparation for division
Prophase
- Chromatin condenses to chromosomes
- Nuclear membrane/envelope starts to break down.
- Spindle fibres form
Late Prophase
- Chromosomes attach to spindle fibres (via centromere)
- Nuclear membrane completes breakdown
- Centrosome is position at poles
Metaphase
Chromosomes line up single file down the centre of the cell
Anaphase
Spindle fibres contract pulling apart the double stranded chromosomes (sister chromatids)
Telophase
Nuclear membrane reforms. Chromosome recondense
Cytokinesis
Cytoplasm splits forming 2 daughter cells (part of M-phase but not mitosis)
Animal cells it forms a cleavage furrow
Plant cells it forms a cell plate
Chromatin
A mixture of DNA and proteins that form the chromosomes
Chromosome
X shaped thingy that carries curled up DNA
Centromere
Middle of the Chromosome
Chromatids
Half of the chromosome
DNA levels between G1 to G2
DNA doubles
Apoptosis
- Controlled cellular death
- Prevents cancer
Name 3 cell checkpoints and explain what it’s for
G1 - verifies that the cell has grown to the correct size, has synthesised enough protein for DNA replication, and checks if the DNA has been damaged during mitosis and cell growth.
G2 - ensures that DNA has replicated properly in the S phase, and that the cell has enough resources for mitosis.
Metaphase - checks the formation of the spindle fibres. If the chromosomes are lined up in the correct location, the cell proceeds to anaphase.
Difference between tumor suppressor genes and proto-oncogenes
Proto-oncogenes - make cells divide when they need to
Tumor suppressor genes - They make sure everything in the cell is as it should be
Mutation in proto - oncogenes causes …
Uncontrollable cell growth
Mutation in tumor suppressor genes
doesn’t stop cell growth
