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111 Cards in this Set
- Front
- Back
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Why does a cell divide?
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To keep from getting too large. To maintain a good surface area to volume ratio.
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What happens when a cell grows?
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When a cell grows, the volume increases faster than the area of the membrane.
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What happens as the volume of a cell grows?
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The membrane becomes unable to move the needed amount of food and oxygen in and out of the cell, so it must divide.
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What is the cell cycle?
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A continuous sequence of events in the life of eukaryotic cells leading to division and duplication.
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What occurs in a cell during interphase?
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All normal metabolic activities and intricate preparations for division.
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What is interphase?
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Interphase is the phase of the cell cycle when the cell is not dividing, and most of the cell's metabolism and growth occur.
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Why does a cell double its chromosomes, organelles and plasma membrane before cell division?
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The cell doubles its structures so that the daughter cells will contain the same structures as the parent cell.
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What is the Growth 1 (G1) Phase?
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The first phase in interphase when most of cell growth occurs while the cell increases size and creates organelles
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What is the Synthesis (S) Phase?
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The S phase is when DNA replication takes place.
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What is the Growth 2 (G2) Phase?
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G2 is the shortest phase of Interphase, when the cell makes more organelles and molecules needed for cell division.
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What is the Mitosis (M) Phase?
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The M Phase is when cell division occurs.
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What occurs during cytokinesis?
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Cytokinesis is the second and last step on M-phase when cystoplasm divides.
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What are the phases of mitosis (M) phase?
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prophase,
metaphase, anaphase, telophase (sometimes cytokinesis is called a phase of mitosis) |
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What is chromotin?
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Long tangled strands of DNA found in the interphase nucleus of eukaryotic cells.
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What happens to the chromosomes during prophase?
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The chromosomes condense, the nuclear membrane disappears, and the newly formed spindle fibers attach to the kinetochore.
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What is the centromere?
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The structure that holds sister chromatids together during prophase.
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What makes chromosomes special in the S phase of prophase?
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The chromosomes are replicated.
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What is the spindle apparatus?
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The proteins that help divide chromosomes during mitosis.
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Where are the chromosomes during metaphase?
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The chromosomes line up on the metaphse plate.
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What occurs during anaphase?
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The chromosome strands are pulled toward the poles.
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What is similar between the daughter cells and the parent cell?
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Normally, the daughter cells have the same structures as the parent cells.
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In plant cells, what forms down the center of the plate at the end of telophase?
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The cell plate.
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What do animal cells contain that plant cells do not have?
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Centrioles.
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What is the dividing state of the cell called?
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mitosis
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What is the "resting" state of a cell called?
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interphase
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Define the cell cycle.
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A sequence of activities exhibited by the cells that alternates between mitosis and interphase.
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When does DNA replication occur?
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during synthesis (the S phase).
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What occurs during mitosis?
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Cells divide.
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What order do the phases G0,G1, G2, S, and mitosis occur?
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G1, G0, S, G2, mitosis
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Gap 0 is:
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A time when the cell leaves the cycle and rests.
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Gap 1 is:
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when cells increase in size, produce RNA, and synthesize protein.
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What must have occurred at the G1 checkpoint for G2 to begin?
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The cell must be big enough, and the environment suitable.
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What is required for the cell to leave G2 and proceed to mitosis?
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The DNA must have replicated, the cell must be big enough, and the environment suitable.
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What must occur for the cycle to proceed with mitosis at the metaphase checkpoint?
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The chromosomes must be aligned on the spindle.
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How long does interphase last in a mammalian cell?
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At least 12 to 24 hours.
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What activities does the cell perform during interphase?
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Synthsizing RNA, producing protein, and growing in size.
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Name a cell that permanently leaves the cell cycle during Gap1 (G1):
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neurons, which are brain cells, and skeetal muscles remain permanently in G1.
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Name a cell that remains permanently in Gap 2 (G2).
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cardiac muscle
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Name three functions of Gap 1 (G1):
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cells increase in size, produce RNA, and synthesize protein
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What does the G1 checkpoint ensure?
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Everything is ready for DNA synthesis.
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What occurs during the S phase?
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DNA replication
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What occurs during G2?
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The sysnthesis of enzymes and other proteins in preparation for mitosis.
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What does the G2 checkpoint ensure?
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The G2 checkpoint ensures that DNA replication in S phase has been completed successfully.
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What stops during mitosis?
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RNA synthesis (cell growth and production)
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What does the cell divide into during mitosis?
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two similar daughter cells
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How long does mitosis last?
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1-2 hours
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What is a zygote?
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A zygote is the diploid cell formed by two gametes after fertilization.
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What cells combine to form a zygote in humans?
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egg and sperm - the fertilized egg is called the zygote
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A cell replicates itself through:
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cell division
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The non-dividing phase of the cell cycle is:
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interphase
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What is the longest phase of the cell cycle?
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interphase
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The amount of DNA in a replicated chromosome is_____ times the amount of DNA in an unreplicated chomosome
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two
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The number of copies of each gene in a replicated chromosome is _____ times the number of copies in an unreplicated chromosome
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two
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Each replicated chromosome contains _____ (insert number) complete copies of genetic information.
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two
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The copies of genetic information in each chromosome are ________________ (identical, homologous, or complementary)
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identical
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How does a human being grow from a single fertilized cell into an individual containing billions of cells?
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Cells increase their number through a process called cytokinesis or cell division.
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Do all the cells of the body contain the same genetic information?
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All cells in the body with the exception of egg and sperm have identical copies of an individual¹s genetic information.
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What does diploid mean?
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there are two copies of each chromosome in the cell
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Are most human cells diploid?
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All human cells are diploid with the exception of sperm and egg cells.
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What human cells are haploid?
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Sperm and egg cells, also known as gametes, are haploid containing 23 chromosomes total.
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Describe homologous chromosomes:
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the same size and shape,
contain the same types of genes in the same order, and generally contain different versions (alleles) of many of their genes. |
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Define homologous chromosomes:
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matching or homologous Chromosomes with similar size and shape, which carry the same genes arranged in the same order.
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Contrast gene and allele:
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A gene is a section of DNA which will code for a particular product. An allele is an alternate form of that gene
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How does a sister chromatids differ from a chromosome?
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A sister chromatid is one-half of a replicated chromosome.
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What is the centromere?
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The centromere is the site on the replicated chromosome where its two sister chromatids are attached.
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What is a chromatid made of?
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A chromatid is made of a very long double helix of DNA, and the DNA is typically surrounded by histone proteins, especially during the condensed phase
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What happens in prophase?
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n prophase, the replicated chromosomes condense and become visible.
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What happens in prometaphase?
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In prometaphase, the nuclear membrane literally disappears, which allows the rest of the mitotic events to occur; spindle fibers form; and Some of the spindle fibers attach to the replicated chromosomes at their centromeres.
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What happens in metaphase?
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Replicated chromosomes are lined up on the metaphase plane (across the center of the cell) by the spindle fibers.
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What happens in anaphase?
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Sister chromatids separate to become daughter chromosomes, and daughter chromosomes are moved toward opposite poles by the spindle fibers..
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What happens during telophase?
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Daughter chromosomes reach the poles of the cell and become extended, and two new nuclear membrane form, one around each set of daughter chromosomes.
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What happens during cytokinesis?
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An animal cell pinches in half at the center, from the outside in, until it has produced two separate daughter cells.
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Interphase
G1 stage |
Growth & development of the cell
Protein synthesis |
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Interphase
S-phase |
Chromosome replication via
DNA synthesis |
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Interphase
G2 stage |
Growth & development
Organelle Replication |
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Prophase
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Replicated chromosomes condense
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Prometaphase
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Nuclear membrane dissolves
Spindle fibers form |
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Metaphase
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Replicated chromosomes align at center
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Anaphase
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Sister chromatids separate
Daughter chromosomes move to pole |
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Telophase
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New nuclear membranes form
Spindle fibers disappear |
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Cytokinesis
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Cell divides into two daughter cells
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Chromosomes are:
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where the DNA of cells is stored.
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Chromatin is:
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the form of chromosomes during interphase.
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What is chromatin after it condenses into an X-shape?
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a discrete, condensed chromosome
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What are the halves of a chromosome called?
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sister chromatids
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What is the protein disc at the middle of a chromosome called?
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centromere
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What are the two steps of cell division?
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Mitosis and cytokinesis.
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During what phase do G1, S and G2 occur?
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interphase
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During what phase do chromosomes condense and become visible?
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prophase
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During what phase do spindle fibers line up the chromosomes on a plane across the center of the cell?
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metaphase
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During what phase are chomatids pulled apart to become daughter chromosomes?
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anaphse
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During what phase do daughter chromosomes reach the poles and relax, and then new nuclear membrane form around them?
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telophase
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When does the nucleus reappear?
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telophase
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When does cytoplasm split in an animal cell?
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cytokinesis
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What are centriole?
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structures at the ends of the cell where spindle fibers emanate.
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What are centrosomes?
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materials that are part of the cytoplasm that are microtubule-organizing centers (MTOCs)
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What is a microtubule (micro tubule)?
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Microtubules are protein structures that help make up the rigid internal cellular structure called the cytoskeleton.
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Where do microtubules originate in animal cells?
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the entrosome
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How many centrioles in a centrosome?
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two
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When is the centrosome duplicated?
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during the S phase or synthesis
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What is a eukaryote?
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an organism whose cells contain complex structures enclosed within membranes.
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What is a prokaryote?
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a group of organisms that lack a cell nucleus or any other membrane-bound organelles.
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How do prokaryotes divide?
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through binary fission
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What happens during binary fission?
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A bacteria cell's chromosome stays in chromatin from and replicates.
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Where do the chromatin attached during binary fission ina prokaryote?
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to the cell membrane at opposite sides of the cell until the cell splits in half to form two daughter cells.
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What cells undergo mitosis?
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eukaryotes
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When does a cleavage furrow occur in animal cells?
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Cleavage furrows develop during cytokineses.
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What occurs at a cleavage furrow?
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It is where the cytoplasm will split to form two daughter cells.
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When are chromosomes duplicated in preparation for cell division?
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During interphase
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Define fission:
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the act of cleaving or splitting into parts.
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Define binary fission:
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In prokaryotes, binary fission is the division of an organism into new organisms as a process of asexual reproduction.
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