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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
Q

DNA segregation-eukaryotes

A

mitosis separates the newly replicated chromosomes into two new nuclei; one copy of each chromosome ends up in each daughter cell

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26
Q

cytokinesis-eukaryotes

A

proceeds differently in animal and plants cells

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27
Q

Binary fission

A

results in reproduction of the entire single-celled organism

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28
Q

interphase

A

G1, S, G2
duration of interphase varies
cell nucleus is visible
typical cell function occurs including replication

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29
Q

G1

A

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

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30
Q

S phase

A

DNA replicates; sister chromatids remain together until mitosis

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31
Q

G2

A

cell prepares for mitosis by synthesizing the structures that move the chromatids

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32
Q

M phase

A

includes mitosis and cytokinesis

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33
Q

Protein kinases

A

enzymes that catalyze transfer of a phosphate group from ATP to a protein (phosphorylation)
this changes shape and function of the protein

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34
Q

CDK

A

controls the G1-to S transition, a control point in the cell cycle called the restriction point

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35
Q

cyclin

A

binds to CDK and changes shape (allosteric regulation), exposing the active site

35
Q

retinoblastoma protein

A

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
Q

CDK regulation

A

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
Q

G1 cyclin-CDK

A

catalyzes the phosphorylation of RB, inactivating RB by changing shape, and no longer blocks the cycle

36
Q

Prophase

A

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
Q

Prometaphase

A

nuclear envelope breaks down
kinetochore microtubules appear and connect the kinetochores on each sister chromatid to opposite chromosomes

38
Q

Metaphase

A

the centromeres of each chromosome become aligned at the equator of the cell

39
Q

Anaphase

A

the pair sister chromatids separate, and the new daughter chromosomes begin to move towards the poles

40
Q

Telophase

A

daughter chromosomes reach the poles; as it ends the nuclear envelopes reform, and the chromosomes de-condense

41
Q

Cytokinesis in animal cells

A

division of cytoplasm
cell membrane pinches in between the nuclei
rind of microfilaments form; the proteins contract and pinch the cell in two

42
Q

Cytokinesis in plant cells

A

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
Q

Asexual

A

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
Q

Sexual

A

offspring are not identical to the parents

45
Q

Gametes

A

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
Q

somatic cells

A

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
Q

Fertilization

A

2 haploid gametes fuse to form a diploid zygote

48
Q

Haploid (n)

A

one copy of each chromosome

49
Q

Diploid (2n)

A

two copies of each chromosome

50
Q

Meiosis 1

A

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
Q

Early prophase 1

A

DNA is loose, centrosomes begin migrating to opposite poles

52
Q

Mid-prophase 1

A

DNA condenses; the 4 chromatids from each homologous pair come together to form a tetrad

53
Q

Late prophase 1-prometaphase

A

crossovers occur between non-sister chromatids at chiasmata

54
Q

Metaphase 1

A

pairs of homologous chromosomes line up on opposite sides of the metaphase plate

55
Q

Anaphase 1

A

the pair of homologous chromosomes separate to different daughter cells

56
Q

Telophase 1

A

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
Q

Meiosis II

A

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
Q

Prophase II

A

chromosomes recondense after a brief interphase in which DNA does not replicate

59
Q

Metaphase II

A

Centromeres of the sister chromatids line up across the metaphase plate of each cell

60
Q

Anaphase II

A

the sister chromatids separate and move to opposite poles
independent assortment of recombinant chromatids contributes to genetic diversity

61
Q

Telophase II

A

the chromosomes gather into nuclei and the cells divide

62
Q

Products of meiosis II

A

each of the cells have a nucleus with a haploid number of unreplicated chromosomes

63
Q

Crossing over

A

exchange of genetic material between non-sister chromatids at the chiasmata

64
Q

Crossing over results in …

A

recombinant chromatids and increases genetic variability of the products

65
Q

Crossing over is one reason for ______ in meiosis 1 products

A

genetic diversity

66
Q

Blending inheritance

A

hereditary determinants blend in the zygote like inks of different colors, once mixed they can no longer be separated (fruit smoothie)

67
Q

Particulate inheritance

A

hereditary determinants are distinct units that remain intact when gametes fuse (fruit salad)

68
Q

Monohybrid crosses

A

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
Q

Dominant and recessive traits

A

The trait that occurred in the F1, and was more abundant in the F2 was called dominant, the other recessive

70
Q

Law of segregation

A

the two copies of a gene separate during gamete formation; each gamete receives only one copy

71
Q

Phenotype

A

observable properties of an individual resulting from both genetic and environmental factors

72
Q

Different traits arise from different forms of a gene

A

alleles

73
Q

Homozygous

A

2 alleles that are the same (RR, rr)

74
Q

Heterozygous

A

2 different alleles (Rr)
One may be dominant and the other recessive

75
Q

Independent assortment

A

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
Q

Human pedigree

A

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
Q

For rare dominant alleles in a pedigree

A

every affected person has an affected parent
about half of the offspring of an affected parent are also affected

78
Q

Incomplete dominance

A

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
Q

Codominance

A

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
Q

Pleiotropic

A

one allele has multiple phenotypic effects

81
Q

Phenylketonuria

A

results from a mutation in the gene for liver enzyme that converts phenylalanine to tyrosine

82
Q

Epistasis

A

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
Q

Quantitative and qualitative

A

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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