Chapter 2 Flashcards
What is the basic unit of life?
The cell
What is cell division in prokaryotes?
A process called Binary Fission, DNA Replication, growth, new plasma membrane and cell wall, 2 new genetically identical cells.
What are Prokaryotes?
-Unicellular, no membrane-bound organelles.
-Prokaryotic DNA doesn’t exist in the highly ordered and packed arrangement, chromosome is circular.
-Made up of bacteria and archaea
- Divide rapidly through binary fission.
What are Eukaryotes?
- Both unicellular and
multicellular with
membrane-bound
organelles - Genetic material is
surrounded in a nuclear
envelope to form a nucleus - Linear DNA is closely
associated with histones to
form tightly packed
chromosomes - Have more DNA
- Multiple linear chromosomes
- More complex division (meiosis/mitosis)
What are viruses?
Neither prokaryotic nor eukaryotic. Outer protein coat
surrounding nucleic acid
(DNA or RNA). Obligate intracellular parasites.
What is a diploid cell?
Cells that carry two sets of genetic information on
homologous pairs of chromosomes.
What is a haploid cell?
Cells that carry one set of genetic information.
What are polyploid cells?
Cells that carry more than two sets of genetic
information.
How many chromosome pairs do humans have?
23 pairs.
What is a Gene?
Represents a region of DNA on a chromosome that codes for something (like hair and eye color).
What is an Allele
Represents a version of that gene (like brown or blue eye color)
What is a Homologous chromosome?
Have the same genes, but may have different alleles.
What is a Sister Chromatid?
Should be genetically identical to each other. Occurs when the DNA has replicated, and the cell is getting ready to divide
What is a histone?
A protein that provides structural support for a chromosome (helps form tightly packed chromosomes)
What are the three parts of a eukaryotic chromosome?
- The Centromere- attachment point for spindle microtubules (kinetocore: protein complex for attachment to spindle fibers at
centromere). - The Telomere- tips of a linear chromosome.
- Origins of Replication-
not easily observed, but needed for
DNA synthesis to begin.
*Sister chromatids also important
What are the four types of chromosomes labeled by the location of their centromere?
Submetacentric, Metacentric, Telocentric, Acrocentric
What is the Cell Cycle?
The steps in the Cell Cycle are the G1, G1/S Checkpoint, S, G2, and M (mitosis). This can then repeat itself, or the cell can go through cytokinesis.
What are the steps in Interphase?
Broken into G1, S, G2 phases (G = gap and
S = synthesis):
G1: cell growth, proteins needed for cell division synthesized.
G1/S Checkpoint: regulated decision point.
S: DNA synthesis
G2: biochemical preparation for cell division
G2/M checkpoint: only passes if DNA completely replicated and undamaged (decided if cell can go through M phase).
What are the steps in M Phase?
Mitosis: separation of sister chromatid.
Cytokinesis: separation of cytoplasm.
What are the 5 parts of Mitosis?
- Prophase: chromosomes condense, spindle begins to form.
- Prometaphase: nucleus disintergrates, kinetochore attach to spindle fibers.
- Metaphase: chromosomes line up in the middle on the metaphase plate.
- Anaphase: chromatids separate.
- Telophase: nucleus begins to reform, chromosomes relax, cell gets ready to physically separate.
* Next is cytokinesis, but that’s separate from mitosis.
What is Cytokinesis?
The separation of cytoplasm. Separate from Mitosis, but part of M phase.
When is DNA replicated?
DNA is replicated during the S phase of the Cell Cycle. During this time, the number of DNA molecules per cell is doubled, up until telophase and cytokinesis.
What is the outcome of Mitosis?
The outcome of mitosis is the production of two genetically identical daughter cells.
What is Meiosis?
The production of haploid gametes
– In multicellular organisms: germ cells produce gametes
– the number of chromosomes is half in gametes
What is Fertilization?
The fusion of haploid gametes.
– generates a diploid organism made up of maternal (mom) and paternal (dad) alleles.
What are the steps of Meiosis?
- Interphase: G1, S - DNA synthesis and chromosome
replication phase, and G2 stages. - Meiosis I: separation of homologous chromosome
pairs, and reduction of the chromosome number by
half - Meiosis II: separation of sister chromatids, also
known as equational division
What are the steps of Meiosis 1?
- Prophase 1: chromosomes condense. Synapsis (close pairing of homologous chromosome). Tetrad (closely associated four-sister chromatids of two homologous chromosomes). Crossing over (crossing over of chromosome segments from the sister chromatid of one chromosome to the sister chromatid of the other synapsed chromosome).
- Metaphase I: random alignment of homologous pairs of chromosomes along the metaphase plate.
- Anaphase I: separation of homologous chromosome
pairs, and distribution of chromosomes into two
newly divided cells. - Telophase: chromosomes arrive at spindle poles
and the cytoplasm divides.
What are the steps of Meiosis II?
- Interkinesis (similar to interphase)
- Prophase II
- Metaphase II
- Anaphase II (chromatids are separated)
- Telophase II (two new nucleotide form)
What is the outcome of Meiosis?
Meiosis creates new combinations of genetic material in each of the four daughter cells. The chromosome number in each new cell is reduced by half; the new cells are haploid.
What is the outcome of meiosis I and II with the mechanism of crossing over?
Each of the resulting cells carry a unique combination of alleles.
What is the outcome of meiosis I and II with the mechanism of random alignment?
There are different ways possible for the pairs to align in metaphase I.
When is DNA replicated during meiosis?
The S phase
What are the types of Meiosis in animals?
Spermatogenesis: male gamete production
Oogenesis: female gamete production
