Cell Physiology Flashcards
1
Q
Homeostasis
A
- Dynamic Equilibrium of the body
- Consistency despite external changes
- Hypothalamus is the body’s control center
2
Q
What does homeostasis control
A
- Nutrients / wastes
- O 2 / CO2 levels
- pH
- Water / electrolytes
- Temperature
- Blood volume
- Blood pressure
3
Q
Negative Feedback
A
- Stimulus, response, stimulus lessens
- Errors include over correction/compensation and competing regulators
- Oscillation is the range that the body is comfortable before a response is triggered
4
Q
Positive Feedback Loops
A
- Response reinforces the stimulus
- Snowball effect
- an external factor is required to shut off the cycle
- ex/ labor
5
Q
Levels of Organization in the body
A
- Chemical (Molecules)
- Cells (basic unit of life)
- Tissue (4 types)
- Organ
- Body system
- Organism
6
Q
Parts of a Cell
A
- cell membrane: controls all interaction w extracellular fluid
- Cytoplasm: cytosol and organelles
- Nucleus: chromosomes and genes
7
Q
Variety of Cells
A
- Shape greatly differs based on function
- Have different organelles to support what it does
ex/ RBC is very small and really only has hemoglobin organelle ar it needs to fit into small vessels and carry lots of oxygen
8
Q
Nucleus
A
- Main Function is replication and repair
- Every cell has one EXCEPT:
1. RBC have none because they need to be able to fold up smaller and they replicate so fast
2. Muscle cells have multiple because they are so long and need repair units to be frequent enough for efficiency
9
Q
Ribosomes
A
- look like the little polka dots in the cell
- responsible for making protein
- the free ribosomes make protein for the cell, while attached ribosomes make protein for export
10
Q
Endoplasmic Reticulum
A
Smooth:
- stores calcium (lots in bone cells)
- Detoxification (lots in liver cells)
- Steroid productions (lots in ovaries)
Rough:
- has ribosomes attached
- makes organelles
- protein production for export
- eg. pancreas makes digestive enzymes for stomach
11
Q
Golgi Complex (Apparatus)
A
- repackages proteins made by RER sp they can be transported outside of the cell
12
Q
Peroxisomes
A
- filled with oxidative enzymes for:
1. metabolism - Beta oxidation, lipid synthesis
2. Detoxify various waste
products, which makes hydrogen peroxide as a byproduct from converting water with catalase
13
Q
Lysosomes
A
- sac of digestive enzymes
- used for repair and removal of
- lots in WBC
14
Q
Proteasomes
A
- large protein complexes
- protein digesting organelles that digest tagged proteins (damaged proteins, incorrectly folded proteins,
proteins no longer needed) - With age, may be unable to
normally remove proteins
15
Q
Cytoskeleton
A
- complex protein network
- like the bone and muscle of a cell for support
- Three distinct elements
1. Microtubules - transport secretory vesicles, Form mitotic spindle during cell division
2. Microfilaments - contractile systems, muscle, Mechanical stiffeners
3. Intermediate filaments - Help resist mechanical stress, in hair, skin, nails
16
Q
Centrosome/Centrioles
A
- there and ready for cell division
17
Q
Cilia
A
- directional and controlled movement of particles
- eg. trachea
18
Q
Flagella
A
- on moving cell
- random non-purposeful movement
19
Q
Mitochondria
A
- energy organelle
- produces ATP
- TCA or krebs cycle
- ECT cycle
20
Q
Aging and our cells
A
- cells deteriorate over time which results in loss of function and inability to respond to stress
- Free radical theory: Damage from byproducts of cellular metabolism
- Mitochondrial theory: A decrease in production of energy weakens cells
- Genetic theory: aging is programmed by genes, With each replication of DNA –nucleotides are lost
21
Q
Plasma Membrane Structure
A
- physical barrier
- gateway for exchange
- communication
- cell structure
22
Q
Phospholipids
A
- Polar coline head (outer layer)
- non-polar fatty acid tails (inner layer)
- prevents free flow in and out of membrane
23
Q
Glycocalyx
A
- Glycoproteins and glycolipids on surface of cell
24
Q
Glycoproteins and proteins on the cell surface
A
- Integral (transmembrane) proteins
- Peripheral proteins (sit on top)
25
Types of membrane Proteins
Ion Channels
Carriers
Receptor sites
Enzymes
Pores
Structural
Cell adhesion
26
Membrane Permeability
- selectively permeable
- Permeable to small, uncharged, nonpolar (lipid soluble) molecules
- transmembrane proteins move polar particles
- macromolecules use vessels
27
Passive Membrane Movement
- no energy required
- powered by gradients (concentration, electrical, and electrochemical)
* Simple diffusion
* Facilitated diffusion
* Osmosis
28
Simple diffusion
- from high to low concentrations
- happens bc of random particle collision
- examples would be oxygen and carbon dioxide as they diffuse from capillaries to RBCs
- two way movement, consider net
29
Rate of diffusion depends on
1. temp - the faster it's moving the more random collisions
2. concentration gradient (bigger diff = faster diffusion)
3. Diffusion distance (less distance = faster)
4. Mass of diffusion substance (bigger = lower velocity = less random collisions)
30
Diffusion across a membrane depends on
- permeability (can it go through?)
- Surface area (lots of openings)
- gradient
- temp
31
Osmosis
- water moving towards solutes
- evening water concentration in relation to solutes
32
Tonicity
- the number of non diffusible particles "water magnets"
- Isotonic - no net difference
- hypotonic - less non diffusible particles
- hypertonic - more non diffusible particles
33
Effects of Tonicity
- crenation: cells shrink in hypertonic solution
- hemolysis: cells rupture in a hypotonic solution
34
Channel Mediated Facilitated
Diffusion
- uses a protein as a channel with no other interaction
- channel must be open
- still according to concentration gradient
- EX/ Na+ and K+ when channels are open
35
Carrier Mediated Facilitated
Diffusion
- requires action by the carrier protein
- Concentration gradient
- Ex/ glucose carrier
36
Active transport
- requires energy as it moves against the gradient
- must use carriers
37
Primary Active Transport
- requires the use of ATP
- Na+, K+ Atp pump for prior to nerve impulses
38
Co-Transport Mechanism
- referred to as secondary active transport
- does not require ATP
- powered by concentration of one solute and the other catches a ride
39
Counter - Transport
Similar to co-transport
but each molecule
moves in opposite
directions
40
Receptor(ligand)-mediated
Endocytosis
- molecules bind to receptor on cell surface
- then brought in in a vesicle
- moves LDLs, fat soluble vitamins, iron, and antibodies
41
Phagocytosis
- process to engulf large molecule from outside of the cell to bring it
- for ex the WBC response to virus would be to bring it in via phagocytosis then allow the vesicle to bind with lysosomes for destruction
42
Pinocytosis
- forms a vesicle via the pinching of the membrane
- used to bring lots of fluid and solutes into the cell
43
Epithelial Transport
- Combines both diffusion and active
transport for movement
- attempts to move the most for the least amount of energy
- ADD TO THIS AS YOU UNDERSTAND
44
Cell Communication
- Important for controlling growth, reproduction, and cellular processes
- Most use ligands (molecules that bind to cell or macromolecules)
- 3 types of receptors that bind ligands:
* Channel-linked receptors
* Enzymatic receptors
* G protein-coupled receptors
45
Channel-linked Receptors
- occurs as a result of neurotransmitter binding
- allows ion channels to open
- Help initiate electrical changes in muscle and nerve cells
46
Enzymatic Receptors
- Protein kinase enzymes
- Phosphorylate other enzymes within the cell
- turns other enzymes on or off
47
G-Protein coupled receptors
- Indirectly activate protein kinase enzymes
- Water soluble so they cant enter the cell without protein
- Activates G-protein to trigger protein kinase or for another channel to open
48
Second Messenger Response
- Shape change of binding protein activates 2nd response inside the cell
49
cAMP response
- Activates protein kinase
- Rapid amplification
50
Calcium as a Messanger
- Activated IP3 causes release of Ca2+ from ER
- DAG and IP3 activate enzymes
51
Calmodulin
- Protein 2nd messenger
- Similar to cAMP response
- Activates protein kinase
52
Genes
- units of heredity
- contain DNA
- each gene has its specific locus (place) on each chromosome
53
Human Chromosomes
- somatic cells have 46 chromosomes with two sets of diploid pairs (one set from each parent)
- Gametes (sperm and egg cells) are haploid cells with only 23 chromosomes, produces from meiosis
54
Cell Division
- process by which cells reproduce themselves
- G1 phase: lasts 8-10hrs where the cell is metabolically active and duplicates organelles
- Interphase (s-phase): lasts 8hrs where DNA is replicated
- G2 Phase: 4-6hr of cell growth
- Mitosis: PMAT
55
Chromosomes
- When preparing for cell division DNA is replicated and chromosomes condense
- Each duplicated (x xhaped) chromosome has two sister chromatids
56
Mitosis: Prophase
- chromatin condense into chromosomes
- nuclear wall degenerates
- centrosomes start to move apart
- spindles move from centrosomes to chromatids
- kinetochore proteins appear
57
Mitosis: Metaphase
- centromeres of chromosomes line up at the midline (metaphase plate)
- mitotic spindles form
58
Mitosis: Anaphase
- centromeres split
sister chromatids move to opposing ends
- kinetochore microtubules move chromatids towards opposing ends of the cell
- Nonkinetichore microtubules overlap and push against each other, to elongate the cell
59
Mitosis: Telophase
- mitotic spindles dissolve
- chromosomes become chromatin
- new nuclear membrane forms
- Cytokinesis: cytoplasm divides, cleavages furrow pinches cell in 2
60
Checkpoints
direct the stages of mitosis and cell growth
61
G1 checkpoint
checks for:
- sufficient nutrients
- big enough cell size
- DNA undamaged
62
G2 checkpoint
Checks for:
- cyclins and cyclin dependent kinases present (2 regulatory proteins)
- Cyclins and Cdks for Maturation promoting factor (MPF) to trigger mitosis
63
External Factors
- things outside of the cell can also cause the start of mitosis
- e.g., growth factor
64
Density dependent inhibition
when cells are crowded they stop dividing
65
Anchorage dependence
cells must be attached to substratum to divide
66
Cancer cells
have no density dependent inhibition or anchorage dependence
67
Apoptosis
- programmed cell death
- to protect us for dysfunctional cells
- tries to get rid of potentially cancerous cells
68
Necrosis
- cell death triggered by inflammation
- not a good process
69
Meiosis
- sexual reproduction
- produces haploid chromosomes
70
Meiosis I
- reduces chromosomes from diploid to haploid
- crossing over: increases genetic variability (little bits of the chromosome switch)
71
Meiosis II
produces 4 haploid daughter cells
72
Gregor Mendel
- discovered basic laws of heredity
- tracked "either-or" characteristics
- hypothesis:
1. there are alternate versions of genes called alleles
2. an organism inherits an allele from each parent
3. if the 2 alleles at a locus differ, the dominant allele appears
4. law of segregation: the 2 alleles for a heritable trait separate during gamete formation
73
Dominant Genetic Disorders
- Disorder is expressed if dominant gene is present
- Seen in heterozygous individuals
74
pedigree
- family tree that describes the interrelationships of parents and children across generations
- Inheritance patterns of traits can be traced
75
Codominance
- two dominant alleles that distinctly impact one phenotype
76
Incomplete dominance
- Phenotype of F1 offspring is between the phenotypes of the two parental varieties
- skin color
77
Pleiotropy
Where one gene has multiple phenotypic
effects
78
Polygeny
- traits are determined by two or more genes
79
X-linked genes
- men only have one x chromosome so they are either the dominant or the recessive gene
- woman have both so they can be heterozygous
80
Gene Expression
- having a gene doesnt mean it is expressed
- Epigenic effects mean we can turn genes on and off based on environmental need
- histones and methylation change it
81
Phenotype
its physical appearance of a specific character
82
Genotype
the genetic makeup (alleles) that determine the physical appearance
83
Alleles
inherited character on the genes (get one from each parent)
84
locus
location on the gene
85
Dominant allele
determines organisms appearance when heterozygous and homozygous
86
Recessive Allele
no noticeable effect on organism unless homozygous recessive
87
Homozygous
- Has a pair of identical alleles for that gene
- Either dominant or recessive
88
Heterozygous
- pair of alleles that are different for that gene.
89
ATP
- cell's energy shuttle
- provides energy for cell functions
- energy is released from ATP when phosphate bone is broken via hydrolysis
90
Carbohydrates
- made of carbon, hydrogen, oxygen
- monosaccarides -
- disaccharides -
- polysaccarides -
91
Proteins
- Made of amino acids
- when broken down AA can be used as energy but better serve other purposes
92
Fats
- glycerol and fatty acids
- more calories per unit
93
Cellular Respiration
- breakdown of glucose or other fuels in the presence of oxygen to yield ATP
- stages
1. glycolysis
2. preparatory step
3. citric acid cycle
4. electron transport system
94
Co Enzymes
- Nad+ becomes NADH (reduced)
- FAD becomes FADH2
- they act as H+ shuttles and therefore move hydrogen ions and electrons to the ETS
95
Glycolysis
- 9 sequential reactions
- Anaerobic (no oxygen needed)
- 2 ATP and 1 Glucose in
- 4 ATP, 2 NADH and 2 Pyruvate out (net 2-2-2)
96
Preparatory Step
- transfer into mitochondria - requires transport protein (controlled by thyroid hormone and thymin)
- loss of CO2
- irreversible (makes choice to go all the way or turn pyruvate into lactic acid for storage)
- pyruvate becomes acetyl coA
97
Citric acid cycle
- occurs in mitochondrial matrix (open gelatinous area)
- 2 acetyl coA therefore two cycles occur
- for 1 acetyl coA 3NADH, 1 ATP, and 1 FADH2 out
98
Electron Transport Chain
- forms ATP
- requires oxygen for this step
- transfers energy from NADH/FADH2 to ADP to for ATP
- Each NADH produces 3 ATP while each FADH2 can produce 2 ATP
- produces 32-34 ATP
99
Flow of energy
- starts as glucose
- creates coenzymes (NADH and FADH2)
- goes to ETC
- creates ATP
100
Glucose
- 1 glucose molecule yields 38 ATP
- oxygen is required for full aerobic process
- only used around 40% of the energy stored in glucose as the remainder is lost as heat
101
Lactic Acid formation
- when there is not enough oxygen
- this is reversible
- allows you to make ATP anaerobically
- when O2 becomes available it can convert back into pyruvate
102
Back up energy sources
- glycogen (stored for of glucose): quickly converts to glucose and is responsible for 1% of energy stores
- Fats: 78% of energy stores and have twice the energy of carbs
- proteins: 21% of energy reserves, but require energy for processing (worst energy source)
103
Protein as Fuel
- AA convert to keto acids
- low ATP yield
- last resort for energy (if you are in starvation or only eat protein)
104
Fat as fuel
- beta oxidation is used to form acetyl CoA - which then enters TCA cycle
- high energy yield
- most efficient storage of energy but it is a slow process
105
Available energy sources for muscle cell
- ready ATP
- creatine phosphate (storage of ATP)
- blood plasma glucose
- glycogen in liver and muscle
- gluconeogenesis (liver)
- fatty acids (diet/storage)
106
Energy systems in exercise
- Immediate: phosphagen (creatine phosphate and ATP), makes 4 moles ATP/min but fatigues in 5-10sec
- Short term: glycolysis (glucose to glycogen-lactic acid), makes 2.5 mole ATP/ min, and takes 1-2 mins to fatigue
- Long term: Aerobic (glucose, AA, fatty acids), makes 1 mole ATP/min and lasts 2+ mins
107
DNA
- Double helix model
- polymer of nucleotides
- a nucleotide is composed of a nitrogenous base, a sugar, and a phosphate group
- has 2 antiparallel sugar phosphate backbones with 3' and 5' ends
- nitrogenous bases are paired in the interior
108
DNA Replication
- Each strand acts as template for building a new strand
- parent unwinds and two daughter strands are built with base pairing rules
- called semi-conservative replication
109
DNA Replication - Helicase
- first step
- helicase unwinds helix
- binding proteins stabilize template strands
- topoisomerase runs ahead and stabilizes the "over twist" sections ahead of helicase
110
DNA Replication - Primase
- Primase primes strands with RNA
111
DNA Replication - DNA polymerase III
- elongates strand, adding nucleotides to 3' end only
- reads parent strand from 3' to 5'
- builds the daughter from 5' to 3'
112
DNA Replication - DNA polymerase I
- replaces RNA primer with proper DNA base nucleotides
113
DNA Replication - Ligase
glues the segments together
114
Leading Strand
- able to synthesize a complementary strand continuously
- moving towards the replication fork
- primase only adds RNA primer once
- DNA polymerase III builds continuously towards fork
- poly I replaces primer
115
Lagging Strand
- synthesized as a series of segments
- called okazaki fragments
- joined together by DNA ligase
- moves away from replication fork
- primase adds to shorter primer sequence
- DNA polymerase III adds nucleotides to 3' end until it reaches next primer (okazaki fragment)
116
Mistake correction in DNA replication
- enzyme cut out and replace damaged stretches of DNA (can be damaged vi sun)
- chromosome ends get shorter every replication
- nucleotide sequences called telomeres postpone the erosion at the ends by being "junk DNA"
117
Stem Cells
- telomerase: catalyzes the lengthening of telomeres in germ cells
118
Protein Functions
- transporters/carriers
- channels/pores
- antibodies
- storage and structure
- hormones and receptors
- contractile proteins
- enzymes
119
Enzymes
- type of protein
- act as a catalyst to speed up chemical reactions
120
Polypeptides
- made up of amino acids
- folds and bends are the secondary structure
- consist of one or more polypeptides (quaternary)
121
Protein Synthesis Overview
- directed by DNA
- one gene codes for one polypeptide
- the ribosome is the cellular machinery for translation
122
Transcription
- synthesis of mRNA under the direction of DNA
- in nucleus
- catalysed by RNA polymerase
- pries DNA strand apart
- hooks together RNA nucleotides (following base pairing rules)
1. Initiation- promoters signal initiation, transcription factor help RNA polymerase to recognize promoter sequence
2. Elongation- RNA polymerase moves along DNA, untwists double helix, exposes 10-20 DNA bases at a time
3. Termination-- polymerase transcribes polyadenylation sequence (AAUAA) so that the protein knows to stop
123
Between transcription and translation
- pre-mRNA
- 5' end receives a modified nucleotide cap
- 3' end gets a poly-A tail
- these help to protect the mRNA nd export it to the cytosol
124
RNA splicing
- removes introns (non-coding) and keeps exons (expressed)
- spliceosomes use snRNP (small nuclear ribonucleoproteins to recognize splice sites
125
tRNA
- translation uses them to shuttle AA to building polypeptide
- Each tRNA is specific for an AA
- anticodon so it binds to a mRNA
- RNA strand with around 80 nucleotides
- Aminoacyl-tRNA synthetase joins each AA to the correct tRNA
126
Ribosomes in protein synthesis
- free in cytosol or bound to ER
- synthesis of all proteins starts on free ribosomes
- export proteins signalled to ER by signal recognition particle (srp)
- facilitate coupling of tRNA anticodons with mRNA codons during protein synthesis
- made of proteins and ribosomal RNA (rRNA)
- has three binding sites for tRNA
1. the A site to add
2. the P site for peptide
3. the E site for Exit
127
Translation - Initiation
- brings mRNA, initiator tRNA (with first AA- Met) and two subunits of ribosome together
- start codon
128
Translation - Elongation
- AA are added one by one to polypeptide
129
Translation - Termination
- ribosome reaches a stop codon in mRNA
130
Poly ribosome
many ribosomes can translate one mRNA at once
131
Mutations
- one wrong nucleotide leads to the wrong AA which leads to a dysfunctional protein
- substitutions, insertions, or deletions can lead to nonsense or mutation
132
Cell Junctions - Tight Junctions
- allows no movement between cells
- E.g., intestine, blood brain barrier
133
Gap junctions
- allows movement of ions between cells (allows a transmission of charge)
- E.g., heart
134
Desmosomes
- Structural junction
- withstands stress (especially in areas that need to stretch)
- E.g., skin, uterus, heart
135
Tissues
cells with similar structure and functions
1. Epithelial
2. connective tissue
3. nerve
4. muscle
136
Epithelial Tissue Overview
- covering sheets all over the body
- glands (endocrine and exocrine)
- functions: protection, absorption, secretion, ino transport, diffusion, filtration, formation of slippery surfaces
137
Epithelial Tissue types
- simple (single layer) vs stratified (multiple layers)
- cuboidal, columnar cell (ex/gut)
- squamous cells - flattened (Ex/lung)
138
Simple Squamous Epithelium
- areas with minimal stress
- adapted for diffusion and filtration (less distance to go)
- Ex/ lung alveoli and bowman's capsule
139
Stratified squamous epithelium
- protects ares with stress
- defends against microbes
- Ex/ outer layer of skin, lining of mouth, vagina
140
Transitional epithelium
- cells that can change shape
- in areas subject to stretching
- urinary bladder
141
Glands
- Exocrine: secrete substances into ducts (sweat glands, gut)
- Endocrine: ductless, secrete hormones (thyroid)
- Paracrine: secrete over short distances
142
The goblet cell
- produces mucin
- mucin + water = mucus
- protects and lubricates many internal body surfaces
143
Connective Tissue overview
- most diverse and abundant tissue
- types: cartilage, bone, blood, fat
- functions: binds, supports, strengthens, protects, insulates, and compartmentalizes muscle
- Protein types: collagen (stiff), elastic (stretchy)
144
Structural Elements of Connective Tissue
- extracellular matrix
- collagen and elastin fibres
- viscous gel-like ground substance
- cushions and protects body structures
- different composition of matrix leads to functional differences
145
Connective Tissue Proper
- two subclasses
1. Loose connective tissue: gel-like matrix with all three fibers, underlies epithelial tissue (fat cells, WBC, mast cells, fibroblasts)
2. Dense connective tissue
*Irregular - collagen and elastin arranged randomly to withstand unknown directions of tension (skin, gut, fibrous capsules of joints and organs)
*Regular - parallel collagen fibers (some elastin) to withstand stress in one direction (tendons, ligaments)
146
Bone - connective tissue
- Compact: harder haversian systems, forms shafts and ends with marrow space - mostly yellow
- spongy: trabeculae form lattice like support, spaces may contain red bone marrow
- bone is 10% cells and 90% matrix
*Cells are osteoblasts (make bone), osteoclasts (reabsorb bone), osteocytes (mature cells)
147
Cartilage - connective tissue
- transitional tissue from which bone develops
- maintains shape of certain body parts (nose, ears)
- cushions vertebrae
- lines joint cavities
- fibrocartilage: IV disks, mensici
- hyaline: embryonic structure (that forms bones later), covers and protects ends of longs
- elastic cartilage: flexible, outer ear, tip of nose
148
Adipose tissue - connective tissue
- fat cells
- insulates, protects, stores energy
149
Muscle Tissue
- contractile for force and movement
- types:
1. cardiac
2. smooth
3. skeletal
150
Nervous Tissue
- signal transmission between brain and nerves
- cells: neurons and neuroglial cells
151
Repair in Nervous tissue
- regeneration: of damaged site with the same type of tissue
- fibrosis: proliferation of scar tissue
- organization: clot os replaced by granulation tissue
152
Capacity for regeneration
- Good/excellent: Et, bone CT, areolar CT, dense irregular CT and blood forming CT
- moderate: smooth muscle
- weak: skeletal muscle, cartilage, dense regular CT
- none or minimal: cardial MT, nervous tissue
153
The Tissues Throughout Life
With increasing age:
- Epithelia thin
- Collagen decreases
- Bones, muscles, and nervous tissue begin to atrophy
- Poor nutrition and poor circulation lead to poor health of tissues
- Decreased healing
