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Biology 100 > Midterm 2 (Ch.5-11) > Flashcards

Midterm 2 (Ch.5-11) Flashcards

1
Q

The cell

A

The basic unit of life (but remember viruses)Unicellular and multi-cellular organisms>200 cell types in humansAll cells share basic components

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2
Q

The microscope

A

• The light microscope • Electron microscope : can be used for viruses and very small things • Anton Van Leewenhoek (1632-1723) ○ Father of microbiology ○ First one to observe blood cells and capillaries.

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3
Q

Phospholipids

A

• The plasma membrane separates the cell from its environment • Consists of a bilayer, mostly of phospholipids • Proteins allow communication between the outside and inside “world” • Fluid Mosaic Model: Membrane components are mobile

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4
Q

The prokaryotic cell

A

No real nucleusLittle internal organization Much smaller than eukaryotes

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5
Q

The eukaryotic cell

A

• DNA contained in the nucleus • Membrane enclosed organelles • Internal compartments of special functions

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6
Q

The cell nucleus, the ‘office’ of the cell

A

Contains the DNASurrounded by a double membrane nuclear envelope The envelope contains pores for molecule transport

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7
Q

The endoplasmatic reticulum, the ‘factory’ of the cell

A

Interconnected tubes and flattened sacs-Rough ER Site of the ribosomes Site for membrane- and secreted proteins-Smooth ER Makes membrane vesicle

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8
Q

The Golgi apparatus, the ‘shipping department’ of the cell

A

Stacked flattened membrane sacsContain enzymes to breakdown macromoleculesRelease simple sugars, amino-acids and fats to be recycledTo clear cell of damaged organellesAs source of foodTo destroy invading bacteria or viruses

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9
Q

Vesicles, movement in the cell

A

Membrane-enclosed sacsTransport vesicles for substance movement from location to location

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10
Q

The lysosomes , the ‘clean-up crew’ of the cell

A

Specialized structure in plants and fungi Breaks down substancesAdds specific chemical groupsTargets them to their destinations

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11
Q

The central vacuole, the storage of the cell

A

Small spherical organelles Processes new proteins and lipids Stores chemicals for later use Fills with water to provide rigidity

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12
Q

The mitochondrion, the power plant of the cell

A

Double-membrane organelleInner membrane folded into cristae Harnesses energy from chemical breakdown Site for cellular respiration – ATP production(Converts Sugars into CO2 and H2O)

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13
Q

The chloroplast, the site of photosynthesis

A

Double-membrane organelleContains grana made of cylindrical sheets called thylakoids Converts CO2 and H2O into sugars using lightChlorophyll enables photosynthesisChlorophyll are embedded in the thylakoid membranes

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14
Q

The cytoskeleton, for the shape and movement of the cell

A

Gives the cell its shapeProvides internal supportIs responsible for movement Microtubules radiate out from the center

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15
Q

Cytoskeleton components

A

–Microtubules Microtubules radiate out from the center Used as tracks for vesicle movement A helical polymer of tubulin monomers Grow or shrink by adding or losing monomers–Intermediate filaments Ropelike filaments Provide structural support–Microfilaments Smallest diameter Made of actin monomers Involved in cell crawling

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16
Q

The amoeba

A

MicrofilamentsInvolved in cell crawling

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17
Q

Cilia and flagella

A

Cilia beat in unison like oars Flagella beat like whips

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18
Q

The bacterial flagellum

A

Very different from eukaryotic flagella H+ ions pumped out of the cellH+ ion entry causes the motion Flagellum rotates like a propeller*run– no change in direction *tumble– change in direction

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19
Q

Evolution of organelles

A

Organelles evolved from prokaryotes engulfing other cells Mitochondria and chloroplasts formedendosymbiotic relationship with the host Eukaryotes most likely evolved from prokaryotesLarger prokaryotes ingested smaller prokaryotesOrganelles evolved from other cells

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20
Q

The plasma membrane, gate and gatekeeper

A

All cells have plasma membraneSeparates the cell from its environmentServes as selectively permeable barrierBiologically important molecules transported across the membraneHydrophobic phospholipid bilayerBarrier to movement: Large and charged moleculesSmall molecules can passhydrophobic molecules can pass

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21
Q

Transport (passive)

A

concentration gradients: areas of abundance to scarcityPassive transportDownhill in energyMovement from high to low concentration

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22
Q

Transport (active)

A

concentration gradients: areas of abundance to scarcityactive transportRequires added energyMovement from low to high concentrationEnergy derided from ATPProduces a concentration gradient

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23
Q

What does DNA turn into and so on… (DOGMA of Biology)

A

DNA to RNA to Protein

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24
Q

Passive transport

A

Small molecules diffuse through membranes ( Phospholipid Bilayer)Larger molecules and ions enter through protein carriers(Channel proteins and Carrier proteins)

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25
Active transport
Active carriers use energy from ATP Energy changes the shape of the carrier Produces a concentration gradient
26
Active carrier proteins
Movement of molecules across a membrane, up a concentration gradient Use energy from breakdown of ATPSodium-potassium pump as an example
27
Osmosis
Water moving passively across the membrane
28
Exocytosis
Release of substances from the cell Vesicles fuse with plasma membrane Fusion with the membrane causes release
29
Endocytosis
Inward budding of the membrane >>>Forms a vesicle 1. Non-specific endocytosis: pinocytosis (‘cell drinking’)2. Specific endocytosis: receptor-mediatedReceptors select targeted substances Only these substances are pull into the cell
30
Phagocytosis
Ingestion of entire cells: ‘cell-eating’Membrane receptors identify the bacterium (for example) Pseudopodia extend around the bacterium
31
Receptors for cell signaling
*hydrophobic -- signaling molecules can pass through the plasma membrane and directly affect processes inside the cell. *hydrophilic-- signaling molecules cannot pass through the plasma membrane and must bind receptors at the cell surface to indirectly affect processes inside the cell. Cell-surface receptors Intracellular receptors
32
Metabolism
The sum of all chemical reactions in the bodyTransfers energy following the laws of thermodynamics
33
Laws of Thermodynamics
First law: Energy cannot be either created or destroyedSecond law: When reactions occur, they become more disordered
34
Metabolism (Anabolism and Catabolism)
The sum of all chemical reactions within living cellsAnabolism:Biosynthetic reactions to create complex molecules out of smaller compoundsCatabolism:Break down reactions of complex molecules to release energy**ATP: the universal energy carrier Energy-storing molecules in all cells
35
The Carbon Cycle and Energy
All living organisms require energy to survive Sun is source of most energy on EarthLight energy is used by producers to synthesize sugars Plants and cyanobacteria perform photosynthesisFor non-photosynthesizing organisms (mostly consumers), energy is acquired from food moleculesCarbon dioxide and food molecules are involved in this energy transfer
36
Using energy from food
Energy transfer in non-living organisms can be explosive (combustion)Energy transfer in cells is controlledCarbon in wood + O2>>>>CO2 + H2O + energy Carbon in food + O2>>>>> CO2 + H2O + energy
37
Electron transfer
Capturing energy requires electron transferReaction that transfer electrons are called redox (Reduction/Oxidation)Oxidation: loss of electronsReduction: gain of electrons
38
Chemical reactions and thermodynamics
Some chemical reactions need a ‘jump-start’ to proceed Activation energy: the energy needed to ‘jump-start’ a reaction
39
Enzymes
Enzymes are biological catalysts
40
Enzymes speed up reactions
They lower the energy of activation They increase the speed of the reaction
41
The structure of enzymes
Very specific for specific reactionsTheir 3D shape determines their function Active site is the region where substrate binds Induced fit: active site ‘molds’ around substrate
42
Enzymes in metabolism
Metabolic pathways in the body usually involve several reactionsThere may be several intermediates Each intermediate has its own enzyme
43
Enzyme function
They depend on random collisionsMultiple enzymes may be located close together This maximizes probability of collision
44
Energy carrier molecules
Receiving, storing and delivering energyUniversal in all cells ATP stores energy in phosphate bondsReleases energy when loses a phosphateATP → ADP → AMPATP: the universal energy carrierEnergy-storing molecules in all cells**NADPH and NADH:High energy molecules that hold energy in the form of electrons and protonsNADPH for anabolism and NADH for catabolism.
45
Evolution of organelles
Larger prokaryotes ingest smaller prokaryotes
46
Photosynthesis and cellular respiration
Exchange of molecules and energy
47
Structure of the chloroplast
Double membrane – inter-membrane space StromaThylakoid discs – Thylakoid space
48
The chloroplast
Double-membrane organelleContains grana made of cylindrical sheets called thylakoids Converts CO2 and H2O into sugars and O2 using light Chlorophyll enables photosynthesisChlorophyll are embedded in the thylakoid membranes
49
The two reactions of photosynthesis
**Light reactionsCapture light energyTakes place in the thylakoidsUse chlorophyllConvert solar energy into chemical energyProduce O2 from H2O**Dark reactions / Calvin CycleTakes place in the stromaUse the energy produced in the light reactionsSynthesize sugar from the fixation of CO2
50
Photosynthesis – the light reaction
Capture of light to Electron transport toATP production • Capture light energy • Takes place in the thylakoids • Use chlorophyll • Convert solar energy into chemical energy • Produce O2 and H2O
51
Photosynthesis- the Dark reaction
• Takes place in the Stroma • Use the energy produced in the light reactions • Synthesize sugars from the fixation of CO2
52
The three steps of cellular respiration
• Glycolysis ○ Breaking down glucose • Krebs cycle ○ Formation of energy carriers • Oxidative phosphorylation ○ Use Oxygen to produce ATP
53
The mitochondrion
Double-membrane organelleInner membrane folded into cristae Harnesses energy from chemical breakdown Site for cellular respiration – ATP production
54
Glycolysis
Glucose split into two pyruvates2ATPs are made
55
Fermentation
• Anaerobic respiration ○ Energy production in the absence of O2 ○ In Yeast and bacteria ○ CO2 and ethyl alcohol produced • In Animals Lactic Acid is produced
56
Krebs Cycle
• Pyruvate converted to acetyl CoA, releasing CO2 • Acetyl CoA enters the cycle • 2CO2, 3NADH, 1ATP are made
57
Oxidative phosphorylation
e- are passed from NADH to e- Transport Chain (ETC)H+ gradients are produced >>>>Drives ATP-synthase >>> (ADP>>ATP)H+ gradients are produced>>>O2 accepts electrons, producing water.
58
Why cells divide?
*Renewal and repair of tissues**Stem cells Capable of self-renewal Give rise to descendant cells**Asexual and sexual reproduction Prokaryotes divide through binary fission Eukaryote cell division in more complex
59
The cell cycle
Series of events in the life of a cellTime to complete cell cycleDependent on organism, cell type, life stageTwo main stages1. InterphaseMost cells spend 90% of lifespan in this stage2. Cell divisionMitosis and cytokinesis
60
Interphase: the longest phase
The period between divisions Longest phase of the cell cycle The cell prepares to divideDivided into three stagesG1: Growth after mitosis S: DNA synthesisG2: Growth before mitosis
61
The G1 and G2 phases
G stands for ‘gap’Early biologists saw a gap between S phase and cell division Periods of growth (cell size and protein content increase) Preparation of next phaseCheckpoint that ensures conditions are suitable
62
The G0 phase
Most cells are not actively dividingCan last days to yearsSome cells will divide again (e.g. liver cells) Some cells stay in Go (e.g. nerve cells)
63
DNA packaged in chromosomes
DNA molecules are enormously long (double helix nearly 2m-long)DNA is tightly packaged with proteins Chromatin: DNA and proteins Chromosome (tightly packed)
64
Karyotype
Chromosomes are visible during mitosis Their number and shape can be studied Humans have 46 chromosomes22 pairs are autosomes (both ch. are homologues)46 ch arranged in 23 pairs One came from each parentOne pair are sex chromosomes Homologous: XX for females Different: XY for males
65
Mitosis
• INTERPHASE BEFORE THE FIVE PHASESConsists of five phases ○ Prophase § Prometaphase □ Metaphase ® Anaphase ◊ Telophase : cytokinesis division of cytoplasm
66
Prophase
Cell enters mitosisChromosomes condenseCentrosomes move apart – go to the poles of the cell Mitotic spindle begins to form
67
Prometaphase
Mitosis proceedsChromosome condensation completed Nuclear envelope breaks downMitotic spindle extends from centrosomesAttaches to centromeres of chromosomesKinetochore: site of attachmentChromatids linked to opposite poles
68
Metaphase
Chromosomes line upMetaphase plateAlign sister chromatids Equal and balanced Segregation
69
Anaphase
Chromatides separateBreak free and dragged to opposite sidesMicrotubules shortenThe result: Equal segregation of chromosomes in two daughter cells
70
Telophase
Chromosomes reach the poles Mitotic spindle falls apart Chromosomes unfoldNuclear membrane reforms
71
Cytokinesis
HAPPENS IN TELOPHASECytoplasm is divided Two cells are formed
72
Meiosis
Used to make gametes [eggs and sperms] Chromosome number is halved (haploid) Zygote is diploid after fertilization   
73
Meiosis 1
Meiosis I reduces the number of chromosomes
74
Meiosis 2
Meiosis II achieves the segregation of sister chromatides
75
Crossing Over
Exchange of genetic material between homologue chromosomesThe product:recombinant chromosomes
76
CH10 | Search for Genetic Material
``` Early geneticists didn’t know what carried genes Contain information Be easy to copy But they knew the substance needed to... Be variable, to account for diversity ```
77
DNA or Protein?
Chromosomes carried genes Which is the genetic material? Protein is large, complex and stores information Chromosomes are composed of DNA and protein DNA seemed too small and unlikely
78
Griffith experiment (1928)
``` Transformation of one strain by another R- harmless Heat-killed S is harmless Two strains of bacteria: Heat-killed S makes R deadly S- deadly ```
79
Hershey and Chase (1952)
*Experiment 1 Radio Active Sulfur labeled protein coat * Experiment 2 Radio Active phosphorous Labeled DNA
80
Watson and Crick (1953)
``` Determined the 3D structure of DNA X-ray crystallographic studies Structure revealed its function Double helix Ladder twisted into a spiral coil ```
81
The double-helix
``` Two long strands of nucleotides Base-pairing holds the strands together Sugar-phosphate backbone *** A pairs with T **** C pairs with G ```
82
Base-pairing rules
``` Strands held together by base-pairing Strict base-pairing rules followed Hydrogen bonds between bases G binds to C A binds to T Makes copying sequence possib ```
83
DNA structure explains function
``` Easily copied DNA sequence is information Each strand is a template for the other A, C, G and T Contained in the order of the four bases Accounts for diversity Millions of bases in length Alleles have different DNA sequences ```
84
Variation and diversity
Individuals have slight differences in sequence Different species have greater differences >98% homologous to humans
85
DNA replication
``` Hydrogen bonds broken Strands unwind and separate Each strand is a template for the other New bases observe base-pairing rules Result is two identical copies ------------------------------------------------------- DNA polymerase Main enzyme involved in replication Many enzymes and proteins are involved Initiate replication Unwind DNA Stabilize the open strands Connect bases to form backbone ```
86
Mistakes
DNA polymerase may insert incorrect bases Mismatch error 1;10,000,000 bases Proofreading enzymes correct mistakes
87
Repair of mistakes
Three steps 1.) Recognize Repair proteins recognize defects in DNA structure 2.)Remove Cut out by special enzymes 3.)Replace Intact strand used as template to fill in the removed gaps
88
Unable to repair
****Inherited disorder in repair Xeroderma pigmentosum Recessive disorder Allele produces non-functional repair protein Cannot repair simple DNA damage from UV exposure Brief exposure to sunlight causes blistering Highly susceptible to skin cancer
89
Lecture #11
The central dogma
90
The central dogma
DNA ---transcription-> RNA --translation--> Protein
91
Information flow
``` Transcription Making RNA In the nucleus Translation Making proteins In the cytoplasm ```
92
RNA versus DNA
``` Both are linear nucleotide polymers RNA has several structural differences Single-stranded Ribose Uracil (U) instead of Thymine (T) ```
93
Three types of RNA
``` Messenger RNA (mRNA) Encodes proteins Transfer RNA (tRNA) Aids in translation Ribosomal RNA (rRNA) Used to make ribosomes ```
94
Transcription: DNA to RNA
``` DNA information is copied into RNA Similar to replication Three differences: RNA polymerase is used Only a small portion of DNA is copied Single-stranded mRNA is made ```
95
The process of transcription
``` RNA polymerase starts at promoter Unwinds DNA Uses one strand (template strand) RNA is synthesized Stops at terminator ```
96
The process of transcription
``` RNA polymerase starts at promoter Unwinds DNA Uses one strand (template strand) RNA is synthesized Stops at terminator *************************************** RNA DNA A - T U --- A C --- G G ---- C ```
97
Introns; non-coding DNA
Non-coding regions of genes Removed after transcription Exons are connected to produce mRNA mRNA is thus the coding sequence of the gene
98
Translation
``` RNA to protein (amino-acid chain) 3 bases = 1 codon 1 codon = 1 amino-acid RNA sequence translated into protein sequence Genetic code used like a dictionary Ribosome Links amino-acids together Hold mRNA ```
99
The genetic code
AUG Methionine; Start Codon | Their is 3 stop codons
100
The genetic code
Possible codons: 4 x 4 x 4 = 64 20 possible amino-acids Most amino-acids have more than one codon - degeneracy Three codons have no amino-acids – stop codons | v From a language of four letters (DNA, RNA) to a language of 20 letters
101
tRNA, the ‘translator’
Two binding sites Amino-acid site Anticodon site Decodes the codon Amino-acid matched with codon
102
Translation
``` Ribosome holds mRNA tRNA binds to first codon – AUG- Methionine Second tRNA binds to next codon Amino-acids are linked Move to next codon – first tRNA is released Repeated till stop codon | v Protein chain ```
103
Mutations
``` Changes in the DNA sequence Causes changes in mRNA sequence, thus in protein Three main types of mutations Substitution--->Changes one amino-acid Insertion--->frameshift Deletion---->frameshift ```
104
The result of mutations
``` ------Frameshift mutations Usually destroy the protein Changes many amino-acids Adds a STOP codon, truncates the protein Changes shape of protein ---------Substitution: single change Silent mutations single amino-acid change ------From gene to phenotype Genes are inherited as DNA DNA is transcribed into RNA RNA is translated into protein Proteins give the organism traits Mutations in DNA produce changes in traits ```
105
From gene to phenotype
Genes inherited as DNA then transcribed into RNA then translated into protein Proteins give the organism traits Mutations in DNA produce changes in traits
106
Sickle cell anemia
One base-pair change in hemoglobin gene One amino-acid change Sickle cell phenotype

Biology 100 (7 decks)

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