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Exam III Flashcards

1
Q

Photosynthesis

A
  • the process that converts solar energy into chemical energy within chloroplasts
  • nourishes almost the entire living world directly or indirectly
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2
Q

Autotrophs

A

“self-feeders” that sustain themselves without eating anything derived from other organisms
- producers of the biosphere

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3
Q

Heterotrophs

A

obtain organic material from other organisms; they are the consumers of the biosphere

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4
Q

the pigment that gives leaves their green color, resides in the thylakoid membranes

A

Plants and other photosynthetic organisms contain organelles called chloroplasts

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5
Q

Chloroplasts are found mainly in cells of the ____, the interior tissue of the leaf

A

mesophyll

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6
Q

CO2 enters and O2 exits the leaf through microscopic pores called

A

stomata

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7
Q

A chloroplast has an envelope of two membranes surrounding a dense fluid called the

A

stroma

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8
Q

____ are connected sacs in the chloroplast that compose a third membrane system

A

thylakoids

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9
Q

Wavelength

A

a measure of the distance between crests of electromagnetic waves•

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10
Q

electromagnetic spectrum

A

the entire range of electromagnetic energy, or radiation

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11
Q

Visible light

A

drives photosynthesis and produces the colors seen by the human eye

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12
Q

Light also behaves as though it consists of discrete particles, called

A

photons

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13
Q

spectrophotometer

A

measures a pigment’s ability to absorb various wavelengths

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14
Q

absorption spectrum

A

a graph plotting a pigment’s light absorption versus wavelength

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15
Q

action spectrum for photosynthesis

A

a profile of the relative effectiveness of different wavelengths, confirms the effectiveness of violet-blue and red light

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16
Q

carotenoids

A

yellow or orange because they absorb violet and blue-green light

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17
Q

photosystem

A

consists of a reaction-center complex surrounded by light-harvesting complexes

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18
Q

reaction-center complex

A

an association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor

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19
Q

light-harvesting complex

A

transfer the energy of photons to the chlorophyll a molecules in the reaction-center complex

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20
Q

primary electron acceptor

A

the reaction center accepts excited electrons and is reduced as a result

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21
Q

Linear electron flow

A

the primary pathway, involves both photosystems and produces ATP and NADPH using light energy

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22
Q

cyclic electron flow

A

photoexcited electrons cycle back from Fd to the cytochrome complex instead of being transferred to NADP+

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23
Q

Interphase

A
  • the cell grows
  • in preparation for cell division
  • chromosomes are duplicated
  • DNA duplicated
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24
Q

Prophase

A

genetic materials inside the nucleus condenses and chromosomes become visible

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25
Pro-metaphase
- nuclear membrane breaks down | - spindle fibers attach to the centromere of the sister chromatids
26
metaphase
spindle fibers move the mitotic chromosomes to the middle of the cell - line up at the cell plate
27
anaphase
sister chromatids are separated and pulled apart. The cell lengthens - chromosomes at opposite poles
28
telophase
spindle fibers disappear and chromosomes uncoil
29
Cytokinesis
the cell divides into two daughter cells, genetically identical to each other and to the parent cell. - the division of the cytoplasm
30
mitosis
the chromosome copies are separated from each other and moved to opposite ends of the cell - the division of the genetic material in the nucleus
31
Somatic cells
(non-reproductive cells) have two sets of chromosomes
32
Gametes
(reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells
33
joined copies of the original chromosome
sister chromatids
34
Centromere
the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached
35
mitotic (M) phase
mitosis and cytokinesis
36
Divisions of interphase
–G1 phase(“first gap”) –S phase(“synthesis”) –G2 phase(“second gap”)
37
mitotic spindle
a structure made of microtubules that controls chromosome movement during mitosis
38
In animal cells, assembly of spindle microtubules begins in the ____
centromere
39
aster
a radial array of short microtubules | extends from each centrosome
40
spindle
includes the centrosomes, the spindle microtubules, and the asters
41
kinetochore
a protein complex associated with centromeres
42
metaphase plate
an imaginary plane midway between the spindle’s two poles
43
Cohesins
a ring of protein complexes that keep the sister chromatids together along their length.
44
In animal cells, cytokinesis occurs by a process known as
cleavage
45
cleavage furrow
a shallow groove in the cell surface near the old metaphase plate
46
In plant cells, a ___ forms during cytokinesis
cell plate
47
Prokaryotes (bacteria and archaea) reproduce by a type of cell division called ____
binary fission
48
In binary fission, the chromosome replicates (beginning at the ____, and the two daughter chromosomes actively move apart
origin of replication
49
The sequential events of the cell cycle are directed by a distinct
cell cycle control system
50
The clock has specific ___ where the cell cycle stops until a go-ahead signal is received
checkpoints
51
Two types of regulatory proteins are involved in cell cycle control:
cyclins and cyclin-dependent kinases (Cdks)
52
MPF
a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
53
If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a non-dividing state called the
G0 phase
54
____ are released by certain cells and stimulate other cells to divide
growth factors
55
In density-dependent inhibition,
crowded cells will stop dividing
56
Most animal cells also exhibit _____—to divide, they must be attached to a substratum
anchorage dependence
57
Cells that acquire the ability to divide indefinitely have undergone
transformation
58
If abnormal cells remain only at the original site, the lump is called a
Benign tumor
59
___ invade surrounding tissues and can undergo ___, the spread of cancer cells to other parts of the body, where they may form additional tumors
malignant tumors | metasis
60
heredity
The transmission of traits from one generation to the next is called inheritance
61
The study of heredity and inherited variation is called ___
genetics
62
Genes
the units of heredity and are made up of segments of DNA
63
Genes are passed to the next generation via reproductive cells called ___
gametes
64
Humans have __ chromosomes in the nuclei of their ___
46 | somatic cells
65
A gene’s specific position along a chromosome is called its
locus
66
In asexual reproduction
a single individual passes all of its genes to its offspring without the fusion of gametes
67
Clone
an individual or group of genetically identical individuals from the same parent
68
sexual reproduction
two parents give rise to offspring that have unique combinations of genes inherited from the two parents
69
life cycle
Is the generation-to-generation sequence of stages in the reproductive history of an organism
70
karyotype
an ordered display of the pairs of chromosomes from a cell
71
The two chromosomes in each pair are called
homologs
72
determine the sex of the individual, are called X and Y
sex chromosomes
73
Human females have a homologous pair of X chromosomes
(XX)
74
Male chromosomes
(XY)
75
The remaining 22 pairs of chromosomes are called
autosomes
76
Human somatic cells have __ pairs of chromosomes
23
77
diploid cell
(2n) has two sets of chromosomes
78
A gamete (sperm or egg) contains a single set of chromosomes and is thus a
haploid cell(n)
79
Each set of 23 consists of __ autosomes and __ sex chromosome - haploid cell
22 | one
80
For humans, the diploid number is
46 (2n= 46)
81
Fertilization
the union of gametes (the sperm and the egg)
82
The fertilized egg is called a ___ and has one set of chromosomes from each parent
zygote
83
Gametes are the only type of human cells produced by ___
meiosis
84
Plants and some algae exhibit an alternation of generations
This life cycle includes both a diploid and haploid multicellular stage
85
Mitosis vs Meiosis: Mitosis
- Occurs in all organisms - Creates body cells - One cell division - no crossing over - 2 diploid cells - identical daughter cells
86
Mitosis vs Meiosis: Meiosis
- animals, plants, fungi - creates sex cells - two cell divisions - crossing over occurs in prophase - 4 haploid daughter cells - daughter cells genetically different
87
meiosis I
–Prophase I –Metaphase I –Anaphase I –Telophase I and cytokinesis
88
Prophase I
each chromosome pairs with its homolog and crossing over occurs
89
X-shaped regions called ___ are sites of crossovers
chiasmata
90
Metaphase I
homologous chromosome line up at the equatorial plate of the cell
91
Anaphase I
pairs of homologous chromosomes separate
92
Telophase I and Cytokinesis
nuclear membrane reforms around the separated chromosomes | - two new diploid cells are formed
93
In animal cells, a__ forms; in plant cells, a __forms
- cleavage furrow | - cell plate
94
meiosis II
–prophase II - metaphase II –anaphase II –telophase II and cytokinesis
95
Prophase II
* In prophase II, a spindle apparatus forms | * In late prophase II, chromosomes (each still composed of two chromatids) move toward the metaphase plate
96
metaphase II
- the sister chromatids are arranged at the metaphase plate | - The kinetochores of sister chromatids attach to microtubules extending from opposite poles
97
Anaphase II
The sister chromatids of each chromosome now move as two newly individual chromosomes toward opposite poles
98
Telophase II and Cytokinesis
* In telophase II, the chromosomes arrive at opposite poles | * Nuclei form, and the chromosomes begin decondensing
99
Crossing Over and Synapsis | A zipper-like structure called the ___holds the homologs together tightly
synaptonemal complex
100
During synapsis,
DNA breaks are repaired, joining DNA from one nonsister chromatid to the corresponding segment of another
101
Three events are unique to meiosis, and all three occur in meiosis I
- 1. Synapsis and crossing over in prophase I –2. Alignment of homologous pairs at the metaphase plate –3. Separation of homologs during anaphase
102
Three mechanisms contribute to genetic variation:
–Independent assortment of chromosomes –Crossing over –Random fertilization
103
Independent Assortment of Chromosomes
In independent assortment, each pair of chromosomes sorts maternal and paternal homologs into daughter cells independently of the other pairs
104
Crossing over produces ____, which combine DNA inherited from each parent
recombinant chromosomes
105
Random Fertilization
Random fertilization adds to genetic variation because any sperm can fuse with any ovum (unfertilized egg)
106
The Evolutionary Significance of Genetic Variation Within Populations
* Natural selection results in the accumulation of genetic variations favored by the environment * Mutations are the original source of different alleles

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