BIOLOGY TEST 3 REVIEW Flashcards
A chromosome contains?
DNA and proteins
What are sister chromatids?
Sister chromatids are are two strands of genetically identical chromosomes
What are chromosomes?
carries genetic information in the form of genes: made up of nucleic acids and proteins
How many chromosomes do humans have?
46
What is the diploid number? What has it?
The diploid (2n) number includes two sets of chromosomes of each type. The diploid number is found in all the non-sex cells of an organism’s body (with a few exceptions).
What is the haploid number? What has it?
he haploid (n) number contains one of each kind of chromosome. In the life cycle of many animals, only sperm and egg cells have the haploid number
What is binary fission?
Binary fission of prokaryotic cells produces two genetically identical daughter cells.
In binary fission, what happens before cell division?
DNA is replicated—both chromosomes are attached to a special site inside the plasma membrane.
In binary fission, what happens after DNA is replicated and the chromosomes have been attached to a special site inside the plasma membrane?
The two chromosomes separate as a cell lengthens and pulls them apart.
In binary fission, what happens after the two chromosomes separate as a cell lengthens and pulls them apart?
A new plasma membrane and cell wall develop and grow inward to divide the cell. When the cell is approximately twice its original length, the new cell wall and plasma membrane for the two daughter cells are complete.
Describe the chromosomes of bacteria. How are they different than eukaryotic chromosomes? What do they look like?
composed of DNA and associated proteins, but much less protein than eukaryotic chromosomes. The chromosome appears as a nucleoid (an irregular-shaped region that is not enclosed by a membrane) The chromosome is a circular loop attached to the inside of the plasma membrane; it is about 1,000 times the length of the cell
What are stages of the cell cycle?
Interphase (G1, S, G2) Prophase, Pro-metaphase, Metaphase, Anaphase, Telophase, Cytokinesis
What happens in the G1 stage? What is it prior to? What happens to the cell/organelles?
just prior to DNA replication; a cell grows in size, organelles increase in number, and material accumulates for DNA synthesis.
What happens in the S stage? What is synthesized? What happens to chromosomes?
The S stage is the DNA synthesis (replication) period; proteins associated with DNA are also synthesized;
at the end of the S stage, each chromosome has two identical DNA double helix molecules, called sister
chromatids.
What happens in the G2 stage? What is it prior to? What is synthesized
The G2 stage occurs just prior to cell division; the cell synthesizes proteins needed for cell division, such as proteins in microtubules.
What is mitosis?
nuclear division. daughter chromosomes are distributed by the mitotic spindle to two daughter nuclei.
What happens in prophase of mitosis?
a. Nuclear division is about to occur: (blank) condenses and (blank) become visible.
b. The (blank) disappears and the (blank) fragments.
c. Duplicated chromosomes are composed of (blank) sister chromatids held together by a (blank);chromosomes have no particular orientation in the cell at this time.
d. The (blank) begins to assemble as pairs of (blank) migrate away from each other.
e. An array of microtubules called (blank) radiates toward the (blank) from the centrosomes.
a. Nuclear division is about to occur: chromatin condenses and chromosomes become visible.
b. The nucleolus disappears and the nuclear envelope fragments.
c. Duplicated chromosomes are composed of two sister chromatids held together by a centromere;
chromosomes have no particular orientation in the cell at this time.
d. The spindle begins to assemble as pairs of centrosomes migrate away from each other.
e. An array of microtubules called asters radiates toward the plasma membrane from the centrosomes.
What happens in pro-metaphase of mitosis? ‘
a. Specialized protein complexes called (blank) develop on each side of the (blank) for future chromosome orientation.
b. An important event during prometaphase is attachment of the chromosomes to the (blank)
c. The kinetochores attach (blank) to the kinetochore (blank)
a. Specialized protein complexes (kinetochores) develop on each side of the centromere for future
chromosome orientation.
b. An important event during prometaphase is attachment of the chromosomes to the spindle.
c. The kinetochores attach sister chromatids to the kinetochore spindle fibers.
What happens in metaphase of mitosis?
a. (blank), attached to kinetochore fibers, are now in alignment at the metaphase (blank), an imaginary plane that indicates the future axis of cell division.
b. Non-attached spindle fibers, called (blank) spindle fibers, can reach beyond the metaphase plate and overlap.
c. A cell checkpoint called the (blank) checkpoint delays the start of anaphase until kinetochores are properly
attached to the spindle fibers, and chromosomes are properly aligned along the metaphase plate.
a. Chromosomes, attached to kinetochore fibers, are now in alignment at the metaphase plate, an imaginary plane that indicates the future axis of cell division.
b. Non-attached spindle fibers, called polar spindle fibers, can reach beyond the metaphase plate and overlap.
c. A cell checkpoint called the M checkpoint delays the start of anaphase until kinetochores are properly
attached to the spindle fibers, and chromosomes are properly aligned along the metaphase plate.
What happens in anaphase of mitosis?
a. The two (blank) of each duplicated chromosome separate at the centromere.
b. (blank) chromosomes, each with a centromere and single chromatid, move toward opposite poles.
i. (blank) spindle fibers lengthen as they slide past each other.
ii. (blank) spindle fibers disassemble at the kinetochores; this pulls daughter chromosomes to
poles.
iii. The motor molecules (blank) and (blank) are involved in this sliding process.
iv. Anaphase is the (blank) stage of mitosis.
a. The two sister chromatids of each duplicated chromosome separate at the centromere.
b. Daughter chromosomes, each with a centromere and single chromatid, move toward opposite poles.
i. Polar spindle fibers lengthen as they slide past each other.
ii. Kinetochore spindle fibers disassemble at the kinetochores; this pulls daughter chromosomes to
poles.
iii. The motor molecules kinesin and dynein are involved in this sliding process.
iv. Anaphase is the shortest stage of mitosis.
What happens in telophase of mitosis?
a. The (blank) disappears in this stage.
b. The (blank) reforms around the daughter chromosomes.
c. The daughter chromosomes diffuse, again forming (blank).
d. The (blank) reappears in each daughter nucleus.
a. The spindle disappears in this stage.
b. The nuclear envelope reforms around the daughter chromosomes.
c. The daughter chromosomes diffuse, again forming chromatin.
d. The nucleolus reappears in each daughter nucleus.
What is cytokinesis?
division of the cytoplasm
What happens in cytokinesis in animals?
a. A (blank) indents the plasma membrane between the two daughter nuclei at a midpoint; this deepens to divide the (blank)during cell division.
b. Cytoplasmic cleavage begins as (blank) draws to a close and organelles are distributed.
c. The (blank) deepens as a band of actin filaments, called the (blank), constricts between the two daughter cells.
d. A narrow bridge exists between daughter cells during (blank) until constriction completely separates the cytoplasm.
a. A cleavage furrow indents the plasma membrane between the two daughter nuclei at a midpoint; this deepens to divide the cytoplasm during cell division.
b. Cytoplasmic cleavage begins as anaphase draws to a close and organelles are distributed.
c. The cleavage furrow deepens as a band of actin filaments, called the contractile ring, constricts
between the two daughter cells.
d. A narrow bridge exists between daughter cells during telophase until constriction completely separates the cytoplasm.
What happens in cytokinesis in plants?
a. The rigid (blank) that surrounds plant cells does not permit cytokinesis by furrowing.
b. The Golgi apparatus produces vesicles, which move along the (blank) to a small flattened disc that has formed.
c. (blank) fuse forming a cell plate; their membranes complete the plasma membranes of the daughter cells.
d. The new membrane also releases (blank) from the new plant cell walls; the cell walls are strengthened by the addition of (blank)
a. The rigid cell wall that surrounds plant cells does not permit cytokinesis by furrowing.
b. The Golgi apparatus produces vesicles, which move along the microtubules to a small flattened disc that has formed.
c. Vesicles fuse forming a cell plate; their membranes complete the plasma membranes of the daughter cells.
d. The new membrane also releases molecules from the new plant cell walls; the cell walls are strengthened by the addition of cellulose fibrils.