Human Genetics
Terms
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- Prokaryotes
- Organisms without a nuclues
- Eukaryotes
- Organishms that have a nuclear membrane surrounding the genetic material and have other membrane-bound organelles in the cytoplasm
- Cytoskeleton
- Asystem of protein microfilaments and microtubules that allows a cell to have a characteristic shape
- Endoplasmic Reticulum
- A system of cytoplasmic membranes arranged into sheets and channels that function in synthesizing and transporting gene products
- Ribosomes
- Cytoplasmic particles composed of two subunits that are the site of protein synthesis
- Golgi apparatus
- Membranous organelles composed of a series of flattened sacs. They sort, modify, and package proteins synthesized in the ER
- Lysosomes
- Membrane-enclosed organelles that contain digestive enzymes
- Mitochondria
- Membrane-bound organelles present in the cytoplasm of all eukaryotic cells that are the sites of energy production within the cells
- Nuclues
- The membrane-bounded organelle in eukaryotic cells that contains the chromosomes.
- Nucleolus
- A nuclear region that functions in the synthesis of ribosomes
- Chromatin
- The component material of chormosomes, visible as clumps or threads in nuclei under a microscope
- Chromosomes
- The threadlike structures in the nucleus that carry genetic information
- Genes
- The fundamental units of heredity
- Homologs
- Members of a chromosomal pair
- Diploid
- the condition in which each chromosome is represented twice as a member of a homologous pair
- Haploid
- The condition in which each chromosome is represented once in an unpaired condition
- Zygote
- The diploid cell resulting from the union of a male haploid gamete and a female haploid gamete
- Centromere
- A region of a chromosome to which fibers attach during cell division. The location of a centromere gives a chromosome its characteristic shape
- Autosome
- Chromosomes other than the sex chromosomes
- Interphase
- The period of time in the cell cycle between mitotic divisions
- Mitosis
- Form of cell division that produces two cells, each of which has the same complement of chromosomes as the parent cell
- Cytokinesis
- The process of cytoplasmic division that accompanies cell division
- G1
- Stage immediately after mitosis-RNA, protein, and other molecules are synthesized
- S
- DNA is replicated. Chromosomes become double stranded
- G2
- Mitochondria divide. Precursors of spindle fibers are synthesized
- Prophase
- 1st stage of mitosis-Chromosomes condense; Nuclear envelope disappears; Centrioles divide and migrate to opposite poles of the dividing cell; Spindle fibers from attach to chromosomes
- Metaphase
- 2nd stage of mitosis-Chromosomes line up on the midline of the dividing cell
- Anaphase
- 3rd stage of mitosis-Chromosomes begin to seperate
- Telophase
- 4th stage of mitosis-Chromosomes migrate or are pulled to opposite poles; New nuclear envelope forms; Chromosomes uncoil
- Chromatid
- One of the strands of a duplicated chromosome, joined by a common centromere, Each chromatid carries identical genetic information
- Synapsis
- The pairing of homologous chromosomes during prophase I of meiosis
- Chiasmata
- The crossing of nonsister chromatids strands seen in the first meiotic prophase. Chiasmata represent the structural evidence for crossing-over
- Crossing-over
- The process of exchanging parts between homologous chromosomes during meiosis, which produces new combinations of genetic information
- Assortment
- The random distrubution of members of homologous chromosomal pairs during meiosis
- Recombination
- The exchange of genetic material between homologous chromosomes. Also known as crossing over
- Interphase I
- Chromosome replication takes place.
- Prophase I
- Chromosomes become visible, homologous chromosomes pair, and sister chromatids become visible. Recombanation takes place
- Metaphase I
- Paired chromosomes align at equator of cell.
- Anaphase I
- Homologous chromosomes separate. Members of each chromosome pair move to opposite poles
- Telophase I
- Cytoplasm divides, producing two cells
- Interphase II
- Following a brief pause, chromosomes uncoil slightly. This is not a real interphase as such
- Prophase II
- Chromosomes re-coil
- Metaphase II
- Unpaired chromosomes become aligned at equator of cell
- Anaphase II
- Centromeres split. Daughter chromosomes pull apart
- Telophase II
- Chromosomes uncoil, nuclear membrane reforms, cytoplasm divides, and meiosis is complete
- Spermatogonia
- Mitotically active cells in the gonads of males that give rise to primary spermatocytes
- Spermatid
- The four haploid cells produced by meiotic division of a primary spermatocyte
- Oogonia
- Mitotically active cells that produce primary oocytes
- Secondary oocyte
- The large cell produced by the first meiotic division
- Ootid
- The haploid cell produced by meiosis that becomes thr functional gamete
- Polar bodies
- Cells produced in the first or second division in female meiosis that contain litlle cytoplasm and will not function as gametes