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Biology 110 > Photosynthesis, cell cycle, and genes > Flashcards

Photosynthesis, cell cycle, and genes Flashcards

1
Q

Light reactions

A

convert light energy to chemical energy as ATP and NADPH
Occurs in the thylakoid membrane

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2
Q

Carbon-fixation reactions

A

uses ATP and NADPH plus CO2 to produce carbohydrates
Occurs in the stroma

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3
Q

Inputs and outputs of light reactions

A

Input: photons/lights and H2O
Output: O2, ATP, and NADPH

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4
Q

Inputs and outputs of carbon-fixation reactions

A

Inputs: ATP, NADPH, CO2
Outputs: G3P -> glucose

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5
Q

Pigment molecules are arranged in _______

A

Light-harvesting complexes or antenna systems

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6
Q

Light energy is captured in _____ and transferred to ______

A

Light harvesting complexes
Reaction centers

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7
Q

The energy is absorbed by other pigment molecules and passed to ______ in the reaction center

A

Chlorophyll a

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8
Q

In the reaction center, the light energy is converted into chemical energy:

A

The excited chlorophyll a molecule (CHI*) gives up an electron to an acceptor
A redox reaction: the chlorophyll gets oxidized to ChI+; the acceptor molecule is reduced
The electron acceptor is the first in a chain of carriers in the thylakoid membrane

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9
Q

ATP is formed by ____

A

photophosphorylation, a chemiosmotic mechanism

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10
Q

H+ is transported across the _______ into the lumen, creating an _______

A

thylakoid membrane
electrochemical gradient

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11
Q

Water oxidation creates more ____ in the lumen and ____ reduction removes ____ in the stroma; both contribute to the __ gradient

A

H+
NADP+
H+
H+

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12
Q

High H+ concentration in the ____ drives H+ back into the stroma through _______

A

lumen
ATP synthase channels

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13
Q

Photosystem I

A

An excited electron from the CHI* reduces an acceptor
The oxidized CHI* takes an electron from the last carrier in PSII
The energetic electron is passed through several carriers and reduces NADP+ to NADPH

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14
Q

Stage one- carbon fixation

A

CO2 incorporated into a 5-carbon molecule (RuBP) by the enzyme rubisco
6-carbon molecule is quickly split into 2 molecules of 3-PGA

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15
Q

Stage 2-reduction

A

Each 3-PGA receives a phosphate from ATP (substrate-level phosphorylation)
These carbon-containing molecules are reduced by NADPH and become G3P

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16
Q

Stage 3- Regeneration

A

Some G3P molecules used to make glucose
Others are recycled to regenerate the 5-carbon RuBP, which is necessary for carbon fixation

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17
Q

C4 plants

A

In mesophyll cells, PEP carboxylase catalyzes the reaction of CO2 and PEP to form oxaloacetate which is converted to malate
Malate diffuses to bundle sheath cells
Malate is decarboxylated to pyruvate and CO2
Pyruvate moves back to mesophyll cells to regenerate PEP
CO2 enters the calvin cycle
ATP has to be spent to ferry intermediates back and forth across the membrane

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18
Q

CAM plants

A

Stomata are open at night and closed during the day to conserve water
At night, CO2 is fixed by pep carboxylase, and malate is stored in vacuoles
During the day, malate moves to chloroplasts and is decarboxylated and the CO2 goes into the calvin cycle
Intermediates are stored in vacuoles until the next day, when photosynthesis can occur

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19
Q

Cell division signals-prokaryotes

A

binary fission begins with cell division signals-usually external factors such as nutrient concentration and environmental conditions

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20
Q

DNA replication-prokaryotes

A

occurs as the DNA moves through a “replication complex” of proteins near the center of the cell. Starts with ori region and ends with ter region

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21
Q

DNA segregation-prokaryotes

A

when replication is complete ori regions move to opposite ends of the cell, segregating the daughter chromosomes

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22
Q

Cytokinesis-prokaryotes

A

cell membrane pinches in; protein fibers form a ring. New cell wall materials are synthesized resulting in in separation of the two cells

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23
Q

Cell signals- eukaryotes

A

related to the needs of the entire organism

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24
Q

DNA replication-eukaryotes

A

eukaryotes have more than 1 chromosome
starts at many origins on the chromosomes
limited to one part of the cell

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25
DNA segregation-eukaryotes
mitosis separates the newly replicated chromosomes into two new nuclei; one copy of each chromosome ends up in each daughter cell
26
cytokinesis-eukaryotes
proceeds differently in animal and plants cells
27
Binary fission
results in reproduction of the entire single-celled organism
28
interphase
G1, S, G2 duration of interphase varies cell nucleus is visible typical cell function occurs including replication
29
G1
chromosomes are unreplicated duration varies from minutes to years or some cells enter a resting phase ends at G1-to-S transition, when commitment is made to DNA replication and cell division
30
S phase
DNA replicates; sister chromatids remain together until mitosis
31
G2
cell prepares for mitosis by synthesizing the structures that move the chromatids
32
M phase
includes mitosis and cytokinesis
33
Protein kinases
enzymes that catalyze transfer of a phosphate group from ATP to a protein (phosphorylation) this changes shape and function of the protein
34
CDK
controls the G1-to S transition, a control point in the cell cycle called the restriction point
35
cyclin
binds to CDK and changes shape (allosteric regulation), exposing the active site
35
retinoblastoma protein
normally inhibits cell cycle, but when phosphorylated by cyclin-CDK, RB becomes inactive and no longer blocks the cell cycle progress past the restriction to progress cycle and cell division
35
CDK regulation
can be regulated by the presence or absence of cyclins must be regulated to progress cycle and cell division CDK's are always present, but cyclins are made only at certain times
35
G1 cyclin-CDK
catalyzes the phosphorylation of RB, inactivating RB by changing shape, and no longer blocks the cycle
36
Prophase
centrosomes move to opposite ends of nuclear envelope microtubules begin to extend from the chromosomes chromosomes are loose at the beginning chromosomes condense and supercoil, becoming more compact and visible kinetochores develop in centromere region; contain motor proteins and provide attachment points for microtubules
37
Prometaphase
nuclear envelope breaks down kinetochore microtubules appear and connect the kinetochores on each sister chromatid to opposite chromosomes
38
Metaphase
the centromeres of each chromosome become aligned at the equator of the cell
39
Anaphase
the pair sister chromatids separate, and the new daughter chromosomes begin to move towards the poles
40
Telophase
daughter chromosomes reach the poles; as it ends the nuclear envelopes reform, and the chromosomes de-condense
41
Cytokinesis in animal cells
division of cytoplasm cell membrane pinches in between the nuclei rind of microfilaments form; the proteins contract and pinch the cell in two
42
Cytokinesis in plant cells
vesicles from the golgi apparatus appear along the plane of cell division, these fuse to form a new cell membrane contents of vesicles form a cell plate-beginning of a new cell wall
43
Asexual
based on mitosis single-celled organism reproduces itself with each cell cycle some multicellular organisms also reproduce asexually aspen trees have shoots that sprout from the root system. All the trees in a stand may be clones of a single parent
44
Sexual
offspring are not identical to the parents
45
Gametes
created by meiosis each parent contributes one gamete gametes and offspring differ genetically from each other and from the parents. Meiosis generates genetic diversity that is the raw material of evolution
46
somatic cells
body cells not specialized for reproduction each somatic cell has homologous pairs of chromosomes with corresponding, but not identical, genes Gametes contain only one set of chromosomes
47
Fertilization
2 haploid gametes fuse to form a diploid zygote
48
Haploid (n)
one copy of each chromosome
49
Diploid (2n)
two copies of each chromosome
50
Meiosis 1
preceded by DNA replication in S phase homologous chromosomes pairs separate, but individual chromosomes (sister chromatids) stay together Two haploid nuclei result, each with half of the original chromosomes (one member of each homologous pair)
51
Early prophase 1
DNA is loose, centrosomes begin migrating to opposite poles
52
Mid-prophase 1
DNA condenses; the 4 chromatids from each homologous pair come together to form a tetrad
53
Late prophase 1-prometaphase
crossovers occur between non-sister chromatids at chiasmata
54
Metaphase 1
pairs of homologous chromosomes line up on opposite sides of the metaphase plate
55
Anaphase 1
the pair of homologous chromosomes separate to different daughter cells
56
Telophase 1
the chromosomes have finished moving to opposite ends of the cell DNA decondenses Cytokinesis finishes cell division At the end of meiosis 1, there are 2 haploid cells
57
Meiosis II
not preceded by DNA replication sister chromatids are separated chance assortment of the chromatids contributes to genetic diversity final products are 4 haploid daughter cells
58
Prophase II
chromosomes recondense after a brief interphase in which DNA does not replicate
59
Metaphase II
Centromeres of the sister chromatids line up across the metaphase plate of each cell
60
Anaphase II
the sister chromatids separate and move to opposite poles independent assortment of recombinant chromatids contributes to genetic diversity
61
Telophase II
the chromosomes gather into nuclei and the cells divide
62
Products of meiosis II
each of the cells have a nucleus with a haploid number of unreplicated chromosomes
63
Crossing over
exchange of genetic material between non-sister chromatids at the chiasmata
64
Crossing over results in ...
recombinant chromatids and increases genetic variability of the products
65
Crossing over is one reason for ______ in meiosis 1 products
genetic diversity
66
Blending inheritance
hereditary determinants blend in the zygote like inks of different colors, once mixed they can no longer be separated (fruit smoothie)
67
Particulate inheritance
hereditary determinants are distinct units that remain intact when gametes fuse (fruit salad)
68
Monohybrid crosses
cross paternal varieties with contrasting traits for a single character F1 are monohybrids Allow plants to self pollinate to produce F2 generation Mendel's results clearly supported the particulate inheritance hypothesis
69
Dominant and recessive traits
The trait that occurred in the F1, and was more abundant in the F2 was called dominant, the other recessive
70
Law of segregation
the two copies of a gene separate during gamete formation; each gamete receives only one copy
71
Phenotype
observable properties of an individual resulting from both genetic and environmental factors
72
Different traits arise from different forms of a gene
alleles
73
Homozygous
2 alleles that are the same (RR, rr)
74
Heterozygous
2 different alleles (Rr) One may be dominant and the other recessive
75
Independent assortment
copies of different genes assort independently the second law is now understood in the context of meiosis chromosomes segregate independently during formation of gametes, and so do any two genes located on separate chromosome pairs
76
Human pedigree
family trees that show the occurrence of phenotypes in several generations of related individuals pedigrees can be used to determine whether a rare allele is dominant or recessive
77
For rare dominant alleles in a pedigree
every affected person has an affected parent about half of the offspring of an affected parent are also affected
78
Incomplete dominance
alleles are neither dominant nor recessive-heterozygotes have an intermediate phenotype In the F2 generation, the original phenotypes reappear, the alleles have not "blended"
79
Codominance
alleles produce phenotypes that are both present in the heterozygote ABO blood group system: 3 different alleles encode an enzyme that adds specific groups to oligosaccharides on red blood cells
80
Pleiotropic
one allele has multiple phenotypic effects
81
Phenylketonuria
results from a mutation in the gene for liver enzyme that converts phenylalanine to tyrosine
82
Epistasis
Phenotypic expression of one gene is influenced by another gene coat color in labs: alleles for black and brown aren't expressed unless allele E is expressed An ee dog is yellow regardless of which B alleles are present. E is epistatic to B
83
Quantitative and qualitative
The pea characters Mendel studied were discrete and qualitative for more complex characters, phenotypes vary continuously over a range- quantitative, or continuous variation, ex height of individuals quantitative variation is usually due to both genes and environment quantitative trait loci: the chromosomal regions that together determine such complex characters; can contain one or several genes

Biology 110 (4 decks)

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