UNIT C (CELL DIVISON, GENETICS, MOLECULAR BIOLOGY) Flashcards
Cell Cycle
The sequence of stages through which a cell passes from
one cell division to the next.
Mitosis
A type of cell division in which a daughter cell receives
the same number of chromosomes as the parent cell.
Chromosome
A threadlike structure of nucleic acids and proteins found in the nucleus of most living cells, carrying genetic information in the form of genes.
Chromatin
The combination of DNA and protein that make up
chromosomes.
Centromere
The structure that holds chromatids together.
Sister Chromatids (NON-Homologous Chromosomes)
A chromosome and its duplicate, attached to one another by a centromere until separated during mitosis.
Homologous Chromosomes
Pairs of chromosomes in a diploid organism that have similar genes, although not necessarily identical. Carries same genes at the same location and carries different forms (alleles) of the same gene.
HUMAN FEMALES HAS HOMOLOGOUS CHROMOSOMES WHILE MEN DO NOT.
Diploid
Refers to twice the number of chromosomes in a gamete.
Haploid
Refers to the number of chromosomes in a gamete.
Polyploid
Stages of Mitosis
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
Interphase (LONGEST phase)
The time interval between nuclear divisions when a cell increases in mass, roughly doubles the cytoplasmic components, and duplicates its chromosomes. Includes G1, S phase and another G2.
G1 Phase
Cells undergo a period of rapid growth, and the chromosomes are unduplicated.
S Phase
Cells begin to prepare for division during interphase by duplicating its chromosomes. At the end of the S phase, all the chromosomes are therefore duplicated chromosomes.
G2 Phase
The cell again grows and it completes the preparations for division (mitosis, or the M phase).
Prophase
- Chromosomes continue to condense. The centrioles assemble and spindle fibres attach to the centromeres of the chromosomes.
- The nuclear membrane starts to dissolve.
- The centrioles move to opposite poles of
the cell and spindle fibres start to form.
Metaphase
- Chromosomes composed of sister chromatids move toward the centre of the cell guided by the spindle fibres.
- Chromatids can become intertwined during metaphase.
Anaphase
- The centromeres divide and the sister chromatids, now referred to as chromosomes, move to opposite poles of the cell.
- Spindle fibres shorten and other microtubules in the spindle apparatus lengthen and force the poles of the cell away from each other.
- Same number and type of chromosomes will be found at each pole. One complete diploid set of chromosomes is gathered at each pole of the elongated cell.
Telophase
- Chromosomes reach opposite poles of the cell and begin to lengthen.
- Nuclear membrane forms.
- The spindle fibres dissolve.
- Chromatids start to unwind into the longer and less visible strands of chromatin.
Cytokinesis
- Cytoplasm begins to divide.
In an animal cell, a furrow develops, pinching off the cell into two parts. This is the end of cell division.
In plant cells, the separation is accomplished by a cell plate that forms between the two chromatin masses. The cell plate will develop into a new cell wall, eventually sealing off the contents of the new cells from each other.
Cell division is stopped by…
Cell specialization. Relatively unspecialized cells, such as skin cells and the cells that line the digestive tract, reproduce more often than do the more specialized muscle cells, nerve cells, and secretory cells.
What two cells divide endlessly?
The sperm-producing cells, called spermatogonia, and the cells of a cancerous tumour. Cancer cells divide at such an accelerated rate that the genes cannot regulate the proliferation and cannot direct the cells toward specialization.
Cloning
A clone originates from a single parent cell, and both the clone and parent have identical (or nearly identical) nuclear DNA. Considered a form of asexual reproduction.
Animal Cloning Technology Order
- Donor mouse developing cells collected
2, Single cells isolated and nucleus extracted - Unfertilized egg removed from recipient mouse
- Nucleus from donor injected into an enucleated egg
- Egg cultured in laboratory
- Cell mass is implanted in the recipient mouse
- Recipient mouse gives birth to the clone mouse (white same as the donor!)