Flashcards in MM 1-4 Deck (48):
Germ line tissue
testes and ovary
2 pairs of chromosome, one from mama, one from papa. Somatic cells
1 pair of chromosomes, having undergone recombination and independent assortment. Egg and sperm cells.
Mutations that occur in meiosis (De novo) are present in egg or sperm. Upon fertilization, the mutated cell replicates and therefore all cells in the offspring contain the mutated gene.
process by which a less specialized cell becomes a more specialized type.
Morphogenesis is the biological process that causes an organism to develop its shape.. I
Micro environmental factors (the niche) provide the signal regulation and support for cells to differentiate.
Where are stem cell found?
found in embryonic cells, tissues, and can be induced in labs.
stem cells able to become all possible types of specialized cells. Embryonic
stem cells that can only make cell found in the type of tissue they belong tofound in skin, gut, marrow, eye, brain, testes..
down field product of stem cells, somewhat differentiated, multipotent, and divide rapidly but do not self renew. End product are cells that perform work and do not divide themselves.
Haematopoietic stem cells (HSC):
Bone marrow. Commited progenitors that become blood cells.
Neural Stem Cells (NSC):
Brain. Committed progenitors become that neurons, dendrites, and astrocytes.
Induced Pluripotent Stem Cells:
Somatic cells reverse engineered to become stem pluripotent cells. Resolves ethical dilemma regarding embryonic stem cells.
Totipotent Stem Cells:
Can become all types of cells, including placenta and umbilical cord. Only exist before 8 cell stage.
Purines: Adenine and Guanine (2 rings)
Pyrimidines: Cytosine, thymine, uracil (1 ring)
What forces hold DNA together?
Hydrogen bonds between bases.
Sugar and phosphate bonded with covalent phosphodiester bond. Stacked bases bonded by van der waals.
Nucleotide: Base, ribose, and phosphate.
Nucleoside: Base & Ribose
How is DNA condensed?
DNA, attracted to the positive charge, wraps around clusters of 8 histones, with another histone between clumps. These bundles are called nucleosomes that have the appearance of bead on a string. Nucleosomes are further consolidated into chromatin fibers, which spiral tightly to form chromosomes..
Clusters containing DNA wrapped around 8 histones, with a 9th in between.
Heterochromatin are segments of chromosomes that are dark in color, tightly packed, and gene poor with no transcription.
Euchromatin are segments of chromosomes that are light colored, loosely condensed, and gene rich with active transcription.
Conserved sequences are similar or identical sequences in nucleic acids across species or within different molecules produced by the same organism. Conservation indicates that a sequence has been maintained by evolution despite speciation. Sequences are only likely to be highly conserved if they are required for basic cellular functions, stability or reproduction.
Accounts for less than 5% of DNA.
Very small, circular, codes for 37 genes, exclusively maternal, & 93% of contains transcribed genes.
The majority of a cell’s cycle, excluding mitosis, when cells grow and replicate their DNA and centrosome.
The first stage after mitosis. The cell grows, produces organelles and proteins, and prepares for DNA replication.
DNA is replicated. This is where point mutations are introduced.
Cell scans replicated DNA for errors before mitosis.
Mitosis: Cell division producing two diploid cells with 46 chromosomes.
Prophase: Transcription ceases; chromatin condenses into sister chromatids, centrosomes move to polar ends, and mitotic spindles form.
Prometaphase: Nuclear envelope breaks down. Spindles seek out kinetochores.
Metaphase: Chromosomes line up in cell center.
Anaphase: Chromatids are separated.
Telophase: Cell divides and nuclear envelope forms.
Cytokinesis: Not a stage of mitosis because not all cell undergo cytokinesis (if they are to have multiple nuclei). Cytokinesis is the process of the membranes merging to make two distinct cells.
The protein structure on chromatids where the spindle fibers attach during cell division to pull sister chromatids apart. Closely associated with the centromere.
Unlike mitosis, chromosomes do not line up, but rather homologous chromosome cross over forming tetrads with genetic recombination. This crossing over mixes the genes from the mother and father. Meiosis 1 then occurs, pulling the tetrads (which are randomly assorted) apart, resulting in each daughter cell having 26 chromosomes (in x form) with newly mixed genes.
In meiosis 2 the chromatids of the 26 chromosomes get pulled apart, resulting in 4 cells that have only one copy of DNA.
when 2 homologous chromosome join up during meiosis 1. Crossing over and recombination occur here.
In what phase of Meiosis does recombination occur?
Independent assortment is the randomness in the direction that the homologous chromosomes are aligned and divided.
When and where does female meiosis occur?
In females, egg cells form while in utero but arrest just before meiosis 1. Later, after puberty, the primary oocyte will undergo meiosis 1 & 2 every month and the cell will divide into four, 3 of which become polar bodies while the other becomes the oocyte. Nondisjunction can occur here during the meiosis.
Recombination occurs during meiosis 1 when the homologous chromosomes align to form tetrads. Chromosomes join one another at the Chiasmata (particular points where crossing over can occur).
Chromosomal sites where homologous chromosomes attach to each other during Meiosis 1. Crossing over occurs here. On average there are 55 chiasmata on male chromosomes and 50% more on womens. So more genetic variance comes from women.
Defect resulting from a single gene defect. Follows Mendelian pattern.