Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
52 Cards in this Set
- Front
- Back
Eukaryotic Cell Cycle |
"Omnis cellula e cellula" means Every cell originates from another cell * Highly regulated series of events that leads to cell division* *All organisms produced by series of repeated rounds of Cell Growth and Division extending back to nearly 4 billion years ago* Cell Division via Mitosis and Meiosis |
|
Mitosis |
Two daughter cell with the same amount of Genetic material as mother cell |
|
Meiosis |
Daughter cells with a single set of Chromosomes Where sexual reproduction happens |
|
Eukaryotic Chromosomes |
The chromosomes become compact enough to be seen with a light microscope, when cells get ready to divide |
|
Cytogenetics |
Field of Genetics involving microscopic examination of chromosomes and cell division |
|
Karyotype |
Reveals number, size, and form of chromosomes in an actively dividing cell |
|
Sets of Chromosomes |
**Humans have 23 pairs of chromosomes** (46 total chromosomes) - Autosomes- 22 pairs in humans - Sex chromosomes- 1 pair in humans * XX= Female or XY= Male |
|
Ploidy |
Diploid or 2n- Humans have 23 pairs of chromosomes (one from mother, one from father) Haploid or n- Gametes have 1 member of each pair of chromosomes or 23 total chromosomes |
|
Homologues |
*In diploid species, members of a pair of chromosomes - similar |
|
Autosomes |
Each Homologue identical in size and genetic composition EX: Both carry gene for eye color but one may have brown and the other blue * Slight difference in sequence can provide large variation in gene function |
|
Sex Chromosomes |
X and Y very different from each other in size and composition |
|
Cell Cycle |
Growth, replication, division to produce new cells M- Mitosis and Cytokinesis G0- Substitutes for G1 for cells postponing division or never dividing again |
|
Interphase Phase Includes |
G1- 1st Gap S- Synthesis of DNA G2- 2nd Gap |
|
G0 Phase |
Nondividing Phase ** Postponed or terminal cell division |
|
Decision to Divide |
** External Factors** - Environmental Conditions - Signaling Molecules **Internal Factors** - Cell cycle control molecules - Checkpoints |
|
G1 Phase (1ST Gap) |
*Cell growth occurs during this phase* ** Signaling molecules can cause cell to accumulate molecular changes during G1 that promote progression through the cell cycle** ** If cell passes the restriction point, or G1 checkpoint, the cell becomes committed to enter S phase and replicate DNA** |
|
S Phase (Synthesis of DNA) |
**Chromosomes replicate** After replication, 2 copies stay joined to each other and are called Sister Chromatids **Human cell in G1 has 46 chromosomes **Same cell in G2 has 46 pairs of Sister chromatids or 92 chromatids total |
|
G2 Phase (2nd Gap) |
Cell synthesizes proteins needed during Mitosis and Cytokinesis |
|
M Phase (Mitosis and Cytokinesis) |
**Mitosis - Division of one cell nucleus into 2 with separation of sister chromatids **Cytokinesis- Follows Mitosis to divide the cytoplasm into 2 daughter cells |
|
Three Checkpoints |
**Critical Regulatory Points**
1) G1 Checkpoint 2) G2 Checkpoint 3) Metaphase checkpoint
** Checkpoint proteins act as sensors to determine if cell are in proper condition to divide
**Cell cycle is delayed until problems fixed or prevented altogether
**Loss of checkpoints can lead to mutations and cancer |
|
G1 Checkpoint |
Restriction point conditions favorable for cell division |
|
G2 Checkpoint |
Levels of proteins required to continue through M phase |
|
Metaphase Checkpoint |
Integrity of the spindle apparatus |
|
Mitotic Cell Division |
** Cell divides to produce 2 new cells genetically identical to the original ** Mother cell is original, Daughter cells are new ** Involves Mitosis- nuclei plus cytokinesis- cells ** Used for asexual reproduction or for development and growth of multi-cellular organisms |
|
Interphase |
Phase of cell cycle during which the chromosomes are decondensed and found in the nucleus (G1, S, G2) |
|
Preparation for Cell Division
|
**DNA replicated then compacted ** Sister Chromatids- 2 identical copies with associated proteins ** Chromatids tightly associated at centromere ** Serves as attachment site for the kinetochore which is later used in sorting chromosomes
|
|
Mitotic Spindle |
** Ensures that each daughter cell will obtain the correct # and types of chromosomes ** Responsible for organizing and sorting the chromosomes during Mitosis ** Composed of microtubles- protein fibers and components of the cytoskeleton |
|
Centrosomes |
Aka Microtubule organizing Center (MTOC) ** Duplicates at the beginning of M phase Each defines a pole |
|
Spindle Microtubules |
Spindle formed from Microtubules
Microtubules formed from Tubulin proteins
|
|
Three types of Microtubules |
1) Astral Microtubules- Position spindle in cell 2) Polar Microtubules- Separate 2 poles 3) Kinetochore Microtubules- Attached to kinetochore bound to centromeres |
|
Mitosis S |
**Process of dividing one cell nucleus into 2 nuclei ** Each daughter cell with complement chromosome - Prophase - Prometaphase - Metaphase - Anaphase - Telophase |
|
Prophase |
** Chromosomes have already replicated and are joined as pairs of sister chromatids ** Nuclear membrane dissociates into small vesicles ** Chromatids condense into highly compated structures that are visible by light microscopy |
|
Prometaphase |
** Nuclear envelope completely fragments ** Mitotic spindle is fully formed during this phase ** Centrosomes move apart and demarcate the 2 poles ** Spindle fibers interact with sister chromatids ** 2 kinetochores on each pair of sister chromatids are attached to kinetochore microtubules from opposite poles |
|
Metaphase |
** Pairs of sister chromatids are aligned along a plane halfway between the poles called the Metaphase Plate ** Organized into a single row ** When alignment is complete, the cell is in metaphase |
|
Anaphase |
** Connections broken between sister chromatids ** Each individual chromatid is linked to only one pole by kinetochore microtubules ** Kinetochore microtubules shorten, pulling chromosomes toward the pole to which they are attached ** The poles move away from each other as overlapping polar microtubules lengthen and push against each other ** Chromatids are equally distributed |
|
Telophase |
** Chromosomes have reached their respective poles and decondense ** Nuclear membranes now re-form to produce 2 separate nuclei |
|
Cytokinesis |
** Mitosis is quickly followed by Cytokinesis in most cases ** 2 nuclei are segregated into separate daughter cells **Process is different in animals and plants** - Animals- Cleavage furrow constricts like a drawstring to separate the cells - Plants- Cell plate forms a cell wall between the two daughter cells |
|
Meiosis and Sexual Reproduction |
** Sexual reproduction requires a fertilization event in which 2 haploid gametes unite to create a diploid cell called a Zygote ** Meiosis is the process by which haploid cells are produced from a cell that was originally diploid - Sperm or egg cell with 23 chromosomes ** 2 rounds of division are necessary |
|
Crossing Over |
** Physical exchange between chromosome pieces of the crossing bivalent ** Increase the genetic variation of a species ** Number of crossovers carefully regulated |
|
Chiasma |
Arms of the chromosomes tend to separate but remain adhered at the crossover site |
|
Meiosis I |
End of meiosis I- 2 haploid cells, with no pairs of homologous chromosomes |
|
Prophase I |
Chromosomes condense, bivalents form and the nuclear membrane breaks down |
|
Prometaphase I |
Spindle apparatus complete, chromatids attach to kinetochore microtubules - Pairs of sister chromatids attached to Single pole |
|
Metaphase I |
Bivalents organized along metaphase plate as double row - Mechanism to promote genetic diversity |
|
Anaphase I |
Segregation of homologues occurs ** Connections between bivalents break, but sister chromatids stay connected together ** Each joined pair of chromatids migrates to one pole, while homologous pair moves to the opposite pole |
|
Telophase I |
Sister chromatids have reached their respective poles and decondense and nuclear membranes reform ** Cytokinesis |
|
Meiosis II |
** No S phase between meiosis I and meiosis II ** Sorting events of meiosis II are similar to those of mitosis ** Sister chromatids separated in anaphase II, unlike anaphase I |
|
Chromosomal Mutations |
** Deletions- Segment of chromosome missing ** Duplication- Repeated segment of chromosome ** Inversions- A segment has a change in direction along a single chromosome (Can break genes at ends or separate from regulatory regions) ** Translocations- One segment becomes attached to another chromosome, may be simple or reciprocal |
|
Euploid |
Normal number of chromosomes ** 2 sets is normal in a diploid organism |
|
Polyploid |
3 or more sets of chromosomes ** Triploid- 3n ** Tetraploid- 4n |
|
Aneuploidy |
Abnormal number of a particular chromosomes **Trisomic- normal 2 copies of a chromosome plus a 3rd 2n+1, ex: Trisomy 21 Down Syndrome ** Monosomic- Missing one of normal copies of a chromosomes 2n-1 |
|
Nondisjunction |
** Chromosomes do not sort properly during cell division ** During meiosis can produce aneuploid gametes |