Biology Midterm

Front 1

Molarity

Back 1

moles solute/ Litres solution

Front 2

Autotrophs vs. heterotrophs

Back 2

a= self feeders, sustain themselves without eating anything derived from other organisms. produces their molecules from CO2, and other inorganic raw materials

h= live on compounds produced by other organisms. are consumers

Front 3

Engelmann's experiment

Back 3

Put light on ala and exposed different segments of the alga to different wavelengths. Violet-vlue and red light releases the most O2 and therefore photosythesize the most

Front 4

Chlorophyll a

Back 4

blue-green
has CH2 molecule in the porphyrin ring

Front 5

Chlorophyll b

Back 5

yellow-green
has CHO molecule in the porphyrin ring

Front 6

G2 of interphase events

Back 6

a nuclear envelope bouds the nucleus
the nucleus contains one or more nucloeoli
two centrosomes have formed by replication of a single centrosome
in animal cells, each centrosome feautres two centrioles
chromosomes, duplicated during S phase, cannot be seen individually because they have not yet condensed

Front 7

Prophase of mitosis

Back 7

the chromatin fibers become more tightly coiled, condensing into discrete chromosomes observable with a light microscope
the nucleoli dissapear
each duplicated chromosome appears as two identical sister chromatids joined together
the mitotic spindle begins to form. it is composed of the centrosomes and the microtubules that extend from them. the radial array of shorter microtubules that extend from the centrosomes are called asters
the centrosomes move away from each other, apparently propelled by the lengthening microtubules between them

Front 8

prometaphase of mitosis

Back 8

the nuclear envelope fragments
the microtubules of the spindle can now invade the nuclear area and interact wit the chromosomes, which have become even more condensed
microtubules extend from each centrosome toward the middle of the cell
each of the two chromatids of a chromosome now has a kinetochore, a specialized protein structure located at the centromere
some of te microtubules attach to the kinetochores, becoming "kinetochore microtubules" these jerk the chromosomes back ad forth
nonkinetichore microtubules interact with those from he opposite pole of the spindle

Front 9

metaphase of mitosis

Back 9

metaphase is the londest stage of mitosis
the centrosomes convene on the metaphase plate, an imaginary plane that is equidistant between the spindle's two poles. the chromosomes' centromeres lie on the metaphase plate.
for each chromosome, the kinetochores of the sister chromatids are attached to kinetochore microtubules coming from opposite poles
the entire apparatus of microtubules is call the spindle because of its shape

Front 10

anaphaseof mitois

Back 10

shortest stage of mitosis
begins when the two sister chromatids of each pair suddenly part. each chromatid thus becomes a full-fledged chromosome
the two liberated chromocomes begin moving toward opposite ends of the cell, as their kinetochore microtubules are attached at the centromere regtion, the chromosomes move centromere first
the cell elongates as the nonkinetochore microtubules lengthen
by the end of anaphase, the two ends of the cell have equivalent and complete collections of chromosomes

Front 11

telophase of mitotis

Back 11

two daughters nuclei begin to form in the cell
nuclear envelopes arise from the fragments of the parent cell's nuclear envelope and other portions of the endomembrane system
the chromosomes become less condensed
mitosis, the division of one nucleus into two genetically identical nuclei, is now complete

Front 12

cytokinesis of mitotis

Back 12

the division of the cytoplasm is usually well underway by late telohpse, so the two daughter cells appear shortly after the end of mitosis
in animal cells, cytokinesis involves the formation of a cleavage furrow, which pinches the cell in two

Front 13

prophase I of meiosis

Back 13

this phase typically occupies more than 90% of the time required for meiosis
chromosomes begins to condense
homologous chromosomes loosely pair along their lengths, precisely aligned gene by gene
in crossing over, the DNA molecules in nonsister chromatids break at corresponding places and then rejoin to the other's DNA
in synapsis, a protein structure called the synaptonemal complex forms between homologues, holding them tightly together along their lengths
the synaptonemal complex disassembles in late prophase, and each chromosome pair becomes visible in the microscope as a tetrad, a group of four chromatids
each tetrad has one or more chiasmata, criss-crossed regions where crossing over has occured, these hold the homologues together until anaphase I
the movement of centrosomes, formation of spindle microtubules, breakdown of the nuclear envelope ,and the dispersal of nucleoli occurs as in mitosis
in late prophase, the kinetochores of each homologue attach to microtubules from one pole or the other. the homologous pairs then move toward the metaphase plate

Front 14

metaphase I of meiosis

Back 14

the pairs of homologous chromosomes, in the form of tetrads, are now arranged on the metaphase plate, with one chromosome of each pair facing each pole.
both chromatids of a homologue are attached to kinetochore microtubules from one pole, those of the other homologue are attached to microtubules from the opposite pole

Front 15

anaphase I of meiosis

Back 15

the chromosomes move toward the poles, guided by the spindle apparatus.
sister chromatids remain attached at the centromere and move as a single unit toward the same pole.
homologous chromosomes, each composed of two sister chromatids, move toward opposite poles.

Front 16

telophase I and cytokinesis of meiosis

Back 16

at the beginning of telophase I, each half of the cell has a complete haploid set of chromosomes, but each chromosomes is still composed of two sister chromatids.
cytokinesis (division of the cytoplasm) usually occurs simultaneously with telophase I, forming two haploid daughter cells.
in animals cells, a cleavage furrow forms
in plant cells, a cell plate forms
in some but not all species, the chromosomes condense and the nuclear envelope and nucleoli re-form
no chromosome replication occurs between the end of meiosis I and the beginning of meiosis II, as the chromosomes are already replicated

Front 17

Prophase II of meiosis

Back 17

a spindle apparatus forms
in late prophase, chromosomes, each still composed of two chromatids, move toward the metaphase II plate

Front 18

Metaphase II of meiosis

Back 18

The chromosomes are positioned on the metaphase plate as in mitosis
because of crossing over in meiosis I, the two sister chromatids of each chromosome are not genetically identical
the kinetochores of sister chromatids are eattached to microtubules extending from opposite poles

Front 19

anaphase II of meiosis

Back 19

the centromeres of each chromosome finally separate and the sister chromatids come apart
the sister chromatids of each chromosome now move as two individual chromosomes toward opposite poles

Front 20

telophase II and cytokinesis of meiosis

Back 20

nuclei form, and chromosomes begin decondensing, and cytokinesis occurs
the meiotic division of one parent cell produce four daughter cells, each with a haploid set of unreplicated chromosomes
each othe the four daughter cells is genetically distinct from the oter daughter cells and from the parentcell.

Front 21

meiosis

Back 21

the union of gametes, culminating in fusion of their nuclei. reduces the number of sets of chromosomes from two to one in the gametes, compensating for the doubling that occurs at fertilization

Front 22

how enzymes lower the Ea barrier

Back 22

enables the reactant molecules to absorbs enough energry to treach the transition state even at moderate tempertaures. only hasten reactions that would occur eventually anyways, bu this funtion makes it possible for the cell to have a dynamic metabolism, routing chemical traffic smoothly throguh thecell.

Front 23

light reactions

Back 23

first part of photosynthesis
are carried out by molecules in the thylakoid membranes
convert light energy to the chemical energy of ATP and NADPH
split H2O and release O2 to the atmosphere

Front 24

Calvin cycle

Back 24

second part of photosynthesis
take place in the stroma
use ATP and NADPH to convert CO2 to the sugar G3P
return ADP, inorganis phosphate, and NADP+ to the light reactions

Front 25

equation for photosynthesis

Back 25

CO2+H2O->CH2O+O2

Front 26

noncyclic electron flow

Back 26

1. a photon of light strikes a molecule in a light harvesting complex and is relayed to other pigment molecules until it reaches one of the two P680 chlorophyll a molecules iin the PS II reaction center. it excites one of the P680 electrons to a higher energy state
2. the electron is captured by the primary electron acceptor
3. an enzyme splits a watermolecule into two electrons, two hydrogens ions, ad an ocygen atom. the electrons are supplied one by one to the P680 molecules, each replacing an electron lost to the primary electron acceptor. the oxygen atom immediately combines with another oxygen atoms forming O2
4. each photoexcited electron passes from the primary electron acceptor of PS II and PS I via an electron transport chain.
5. the exergonic fall of electrons to a lower energy level provides energy for the synthesis of ATP
6. meanwhile, light energy was transferred via a light-harvesting complex to the PS I reaction center, exciting an electron of one of the two P700 chlorophyll a molecules located there. the photoexcited electron was then captured by PS I's primary electron acceptro, creating an electron hole in the P700. the hole is filled by an electron that reaches the bottom of the electron transport chain from PS II.
7. photoexcited electrons are passed from PS I's primary electron acceptor down a second etc
8. the enzyme NADP+ reductase transfers two electrons for reduction to NADPH.

Front 27

cyclic electrom

Back 27

only uses photosystem I
no production of NADPH or O2. generates ATP. cell needs atp because calvin cycle consumes more ATP than NADPH

Front 28

purple wave length
red wave length

Back 28

380
750

Front 29

redox reactions

Back 29

oxidation, the loss of electrons from one substances

reduction, the addition of electrons to another substance

reducing agent accepts donated electron
oxidizing agent removes the electron

Front 30

glycolysis

Back 30

in cellular respiration
turns glucose into 2 pyruvate, 2 H2O, 2 ATP, 2 NADH and 2 H+

Front 31

phosphofructokinase

Back 31

in cellular respiration transers a phosphate group from ATP to the sugar investing another molecule of ATP in glycolysis. allosterically regulated by atp and its products.

Front 32

citric acid cycle/ Krebs cycle

Back 32

in cellular respiration
starts after pyruvate is converted into acetyl co-a
turns into citrate, then oxaloacetate
two turns produces: Co2, 6 NADH, 2 ATP, 2 FADH2

Front 33

pyruvate-> acetyl coa

Back 33

gives off co2, nadh, and makes co a