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1

cell division

is the process by which a cell doubles its organelles and cytoplasm, replicates its DNA, and then divides in two

2

unicellular organisms

cell division is a means of reproduction

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multicellular organisms

is a method of growth, development, and replacement of worn-out cells

4

mitosis

is the division and distribution of the cell's DNA to its two daughter cells such that each recieves a complete copy of the original genome

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karyokinesis

nuclear division

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cytokinesis

cell division

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interphase

a period of growth and replication of genetic material prior to the initiation of mitosis

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prophase

the chromosomes condense, and the centriole pairs separate and move towards the opposite poles of the cell. The spindle apparatus forms between them and the nuclear membrane dissolves, allowing the spindle fibers to interact with the chromosome

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metaphase

the centriole pairs are now at opposite poles of the cell. The fiers of the spindle apparatus attach to each chromatid at the centromere to align the chromosomes at the center of the cell forming the metaphase plate

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anaphase

the centromeres split so that each chromatid has its own distinct centromere, thus allowing sister chromatids to separate. The sister chromatids are pulled toward the opposite poles of the cell by the shortening of the spindle fibers.

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telophase

the spindle apparatus disappears. A nuclear membrane forms around each set of newly formed chromosomes. Thus each nucleus contains the same number of chromosomes as the original or parent nucleus. The chromosomes uncoil, resuming their interphase form

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cytokinesis

near the end of telophase, the cytoplasm divides into two daughter cells, each with a complete nucleus and its own set of organelles

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cleavage furrow

in animal cells,. The cell membrane indents along the equator of the cell and finally inches through the cell, separating the two nuclei

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plant cells

lack centrioles. The spindle apparatus is synthesized by microtubule organizing centers which are not visible. Are rigid and cannot form a cleavage furrow. They divide by the formation of a cell plate

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cell plate

an expanding partition that grows outward from the interior of the cell until it reaches the cell membrane

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meiosis

is the process by which these sex cells are produced. Produces the haploid (!N) number, halving the number of chromosomes. Involves two divisions of primary sex cells resulting in four haploid cells called gametes

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interphase

the parent cell's chromosomes are replicated during interphase resulting in the 2N number of sister chromatids

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first meiotic division

the first division produces two intermediate daughter cells with N chromosomes with sister chromatids

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prophase I

the chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear

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synapsis

homologous chromosomes come toggether and intertwine

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tetrad

each synaptic pair of homologous chromosomes contains four chromatids

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crossing over

chromatids of homologous chromosomes break at corresponding points and exchange equivalent pieces of DNA

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metaphase I

homologous pairs (tetrads) align at the equatorial plane, and each pair attaches to a separate spindle fiber by its kinetochore

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anaphase I

the homologous pairs separate and are pulled to opposite poles of the cell

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disjunction

each chromosome of paternal origin separates (or disjoins) from its homologue of maternal origin, and either chromosome can end up in either daughter cell

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telophase I

a nuclear membrane forms around each new nucleus. At this point, each chromosome still consists of sister chromatids joined at the centromere

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second meiotic division

the chromosomes aligh at the equator, separate and move to opposite poles, and are surrounded by a reformed nuclear membrane

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asexual reproduction

is the production of offspring without fertilization

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fission

binary fission is a simple form of asexual reproduction seen in prokaryotic organisms. The DNA replicates and a new plasma membrane and cell wall grow inward along the midline of the cell, dividing it into two equally sized cells with equal amounts of cytoplasm, each containing a duplicate of the parent chromosome

30

budding

is the replication of the nucleus followed by unequal cytokinesis. The cell membrane pinches inward to form a new cell that is smaller in size but genetically identical to the parent cell, and which subsequently grows to adult size. The new cell may separate immediately from the parent or it may remain attached to it, develop as an outgrowth, and seaparate at a later stage