Bio Exam 3

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Centromere

Back 1

Region of constricted DNA which holds 2 chromatids together

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Nucleosome

Back 2

Consists of a DNA molecule wound around a core of 8 histone proteins

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Nucleolus

Back 3

An accumulation of both RNA molecules and structural proteins. Forms near a particular region of a particular chromosome, which contains the genes responsible for the production of these molecules. Used in the assembly of ribosomes.

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Ribosome

Back 4

Cytoplasmic particle consisting of 2 subunits synthesized in the nucleus. Assembled by RNA molecules and structural protein molecules. The subunits pass through the nuclear envelope into the cytosol. Form the this object "on demand"

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Two principle stages of the Cell Cycle

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Interphase, M (Mitotic) Phase

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Interphase consists of

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G1 Phase, S Phase, and G2 phase

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G1 phase

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Variable in length..checkpoint to "decide" whether or not the cell will divide again...if yes..multiplication of organelles, rapid growth and increase in size

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G0

Back 8

cells that are arrested in G1 for long periods are said to be in this state

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G

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Gap--G1, gap b/w M phase and S phase, G2 is gap between Sphase and M phase

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S Phase

Back 10

Synthesis of DNA in which each chromosome is being replicated to form a pair of identical chromatids; centrosome replicates

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G2 Phase

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Cell attains its full, mature size, all functions essential to the life of the cell are occuring, final preparations for m phase, synthesis of protein tupulin for hte production of microtubules

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Microtubules

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Production of Microtubules begins during the G2 phase. Tubulin is created, and the tubulin subunits are assembled into long fibers called microtubules.

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Centriole

Back 13

Center for production of microtubules, consists of microtubules

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Asters

Back 14

Consists of microtubules in the shape of a sunburst

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90% of Cell Cycle

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Interphase (%)

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M Phase

Back 16

Consists of cytokinesis and mitosis

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Mitosis

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division of nucleus

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Cytokinesis

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Division of cytoplasm

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5 Stages of Mitosis

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Prophase, prometaphase, metaphase, anaphase, telophase

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Prophase

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Mitotic spindle begins to form, consists of microtubular fibers which extend between the two centrosomes. Centrosomes begin movement to opposite sides of the cell

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Chromosome consists of

Back 21

2 Sister Chromatids

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Prometaphase

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Nuclear envelope disassembled, microtubule from one pole attaches to kinetochore of one one member of a chromatid pair, and microtubule from opposite pole attaches to kinetochore of the other member of the pair

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Nonkinetochore Microtubules

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Cross-linking proteins between microtubules from opposite poles, push microtubules apart in anaphase

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Metaphase

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Longest of the phases, alignment takes place midplane, centromeres of chromatid pairs are aligned on this plane, pulls toward opposite poles are exactly balanced

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Anaphase

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Shortest stage; centromeres divide, chromatid pairs are broken, begins to reduce the supercoiling of the chromatin, so the centromeres divide, new chromosomes are formed from the breaking chromatids

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Motor Proteins

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Pull the kinetochore and new chromosome to the pole

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Depolymerization

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Tubulin units are broken apart

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Telophase

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Nuclear envelopes form around new nuclei, nucleoli are reconstituted, chromatin becomes diffuse (not visible), now overlapping cytokinesis

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Cleavage furrow

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groove that forms in the region of the formerly identified midplane

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Microfilaments

Back 30

band of structures immediately inside the cell membrane, consist of contractile proteins

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Plant Cells with Rigid cell wall

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rigid due to cellulose

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Golgi Apparatus

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Function: to package and redistribute molecules synthesized in the cell

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Membrane Vesicles

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directed to midplane by phragmoplast, contains cellulose, parallel array of remains of former nonkinetochore microtubules

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genetics

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the study of: hereditary and variation; how characteristics of parents are inherited by their offspring

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gene

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-Fundamental unit of inheritance
-A sequence of nucleotides in a DNA molecule

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Locus

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the position of the gene on the chromosome

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genetic cross

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A mating of sexually reproducing organisme

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True breeding

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Genetically pure; homozygous for the specific genes that control the characteristics under consideration

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Offspring of True-Breeding parents

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genetically identical to the parents in respect to the characteristics under consideration

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Hybridization

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cross between parents genetically dissimilar in respect to characteristics under consideration

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Offspring of dissimilar parents

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Dissimilar to both parents

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Punnett Square

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a format for representing a genetic cross

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Monohybrid

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describes the inheritance of the alleles of a single gene (locus)

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Dihybrid Cross

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Inheritance of the alleles of two genes (loci)
Each gene controlled by complete dominance

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Meiotic Cell Division

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Essential for sexual reproduction
Division of 1 specialized diploid (2n) cell to yield 4 haploid (n) cells (gametes)

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Gametes

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Haploid cells resulting from meiosis

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Meiotic Cell division consists of

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Meiosis, Cytokinesis

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Principle of Independent Assortment

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The alleles of genes on non-homologous chromosomes segregate independently of one another during meitoci cell division

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2 types of nucleic acid

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DNA & RNA; both polymers

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Genome

Back 50

the total complement of an organism's genetic information; this information is stored as the sequences of nucelotides in DNA molecules

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Genes in Nucleotides

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a specific sequence of nucleotides in a DNA molecule; each gene codes for the synthesis of a specific protein (polypeptide)

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Polypeptide

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chain of covalently bonded amino acids, which determines the sequences of amino acids in a protein

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Enzymes

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protein molecules; essential catalysts in the reactions of metabolism

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Nucleus

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Comprehensive function is to regulate and control the cell; conducts this function by directing the synthesis of enzyme proteins

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3 Components of Nucleotides

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Pentose (5-Carbon) sugar
Phosphate group
Nitrogenous Base

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Two Classes of Nitrogenous Bases

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purines
pyrimidines

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purines

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adenine, guanine (in both DNA & RNA)

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pyrimidines

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cytosine (in DNA & RNA), thymine (DNA), uracil (RNA)

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Double Strand

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In either strand of the double helix, any 2 nucleotides may be adjacent to one another and covalently bonded...endless possibilities for sequences of nucleotides in either strand

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Complementary Base Paring

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Purines and pyrimidines are positioned directly opposite one another

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What holds the 2 strands of the double helix together?

Back 61

Hydrogen bonds

Front 62

How many bonds between adenine and thymine?

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2

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How many bonds between cyanine and guanine?

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3

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phragmoplast

Back 64

parallel array of remains of former nonkinetochore microtubules

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topoisomerase

Back 65

enzyme which begins to reduce the supercoiling of the chromatin, necessary for centromere division