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Biological reproduction
________, with continuing evolutionary selection for a highly functional body plan, is why todays horseshoe crabs look much as they did 300 million years ago.
G1
The M and S phases are separated by two gap stages, the** ________ phase and G2 phase,** during which mRNAs and proteins are made.
ATP
To create the low pH environment, proteins located in the** lysosomal membrane** pump hydrogen ions into the** lysosome** using energy supplied from ________.
Cells
________ can produce a particular** mRNA** only when the encoded protein is needed, thus minimizing wasted energy.
unique functions
The ________ and micro- climates of the various cell compartments are due largely to the proteins that reside in their membranes or interior.
ionic composition
The cytosol and the internal spaces of organelles differ from each other and from the cell exterior in terms of** acidity, ________, and protein contents**
Teton Mountains
The ________ in Wyoming, now about 14, 000 feet high and still growing, didn't exist a mere 10 million years ago.
plasma membrane
The cytoskeleton prevents the ________ of animal cells from relaxing into a sphere it also functions in cell locomotion and the intracellular transport of** vesicles**,** chromosomes**, and** macromolecules**
asexual process
Mitosis** is a(n) ________ since the daughter cells carry the exact same genetic information as the parental cell.
complex macromolecules
Directly or indirectly, all of our food is created by plant cells using sunlight to build ________ during** photosynthesis**
cytoplasm of fat
The circulating insulin signal causes glucose transporters in the ________ and muscle cells to move to the cell surface, where they begin importing glucose.
E coli cells
________ prefer glucose as a sugar source, but they can survive on lactose in a pinch.
Elaborate systems
________ regulate the assembly and disassembly of the cytoskeleton, thereby controlling cell shape.
Gene expression
________, the overall process of selectively reading and using genetic information, is commonly controlled at the** level of transcription**, the first step in the production of proteins.
Mobile elements
________, which were discovered first in plants, are responsible for leaf color variegation and the diverse beautiful color patterns of Indian corn kernels.
ribosomes
Proteins are secreted from the cell and most membrane proteins are made on ________ associated with the endoplasmic reticulum (ER)
abundant protein
Collagen**, the single most ________ in the animal kingdom, is a major component of the extracellular matrix in most tissues.
fundamental defect
The ________ in cancer is the loss of the ability to control the growth and division of cells.
membrane proteins
The attachment of some ________ to other molecules inside or outside the cell restricts their lateral movement.
eukaryotic cells
Most of the DNA in ________ is located in the nucleus, extensively folded into the familiar structures we know as** chromosomes**
Plants
________ have a less distinct division between somatic and germ- line cells since many plant cells can function in both capacities.
tough matrix
A specialized, especially ________, the basal lamina, forms a supporting layer underlying sheet- like cell layers and helps prevent the cells from ripping apart.
phospholipid layers
The two** ________ of** a membrane are oriented with all the** hydrophilic ends** directed toward the inner and outer surfaces and the hydrophobic ends buried within the interior.
sexual reproduction
In** ________**, the fusion of two cells produces a third cell that contains genetic information from each parental cell.
bacterial cells
Like ________,** unicellular eukaryotes** may be subjected to widely varying environmental conditions that require extensive changes in cellular structures and function.
cell surface
The binding of many other** hormones** and of growth factors to receptors on the ________ triggers different signal- transduction pathways that also lead to changes in the transcription of specific genes.
genome of an organism
The ________ comprises its entire complement of DNA.
hormone insulin
The rise in blood glucose is sensed by cells in the pancreas, which respond by releasing their stored supply of the** protein ________**
circular DNA
This is the ________ present in mitochondria, the organelles in eukaryotic cells that synthesize ATP using the energy released by the breakdown of nutrients.
DNA polymerase
________**, which is responsible for linking nucleotides into a DNA strand.
eukaryotic cell cycle
The ________ commonly is represented as four stages.
steroid hormones
Since ________ can circulate in the bloodstream, they can affect the properties of many or all cells in a temporally coordinated manner.
Cells
________ need to break down worn- out or obsolete parts into small molecules that can be discarded or recycled.
ribosomes
Some proteins are made on ________ that are free in the** cytosol**
Mobile elements
________ were later found in bacteria which they often carry and, unfortunately,** disseminate genes** for antibiotic resistance.
plasma membrane
The** ________** and other cellular membranes are composed primarily of two layers of phospholipid molecules.
Cells
________ possess numerous receptor proteins for detecting signals and elaborate pathways for transmitting them within the ________ to evoke a response.
Cells
________ can move at rates on the order of 20 m /second.
