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.
What are spindle fibers
Just outside the nucleus is the centrosome. (in animals it contains centrioles)
Centrosome organizes the mitotic spindle. The spindle contains many fibers. Each fiber is composed of a cylindrical bundle of microtubules. Microtubules assemble when tubulin subunits join and when the subunits disassemble they form mitotic spindle fibers
How many chromosomes are in each cell after mitosis and cytokinesis?
46
What is the centromere?
a region of constriction on a chromosome. Holds together sister chromatids of a chromosome
What is meiosis? What does it do to the number of chromosomes? What does it involve?
nuclear division, reducing the chromosome number from the diploid (2n) to the haploid (n)number. Meiosis involves two nuclear divisions and produces four haploid daughter cells. Each daughter cell has half the number of chromosomes found in the diploid parent nucleus.
What happens in Meiosis I? What happens prior to it? How many chromatids? What is formed? What process occurs?
Prior to meiosis I, DNA replication occurs, each chromosome thus has two sister chromatids. b. During meiosis I, homologous chromosomes pair forming a synaptonemal complex; this process is called synapsis. During synapsis, the two sets of paired chromosomes lay alongside each other as a bivalent (sometimes called a tetrad).
What happens in Prophase I?
1. (blank) is about to occur: (blank) disappears; (blank) fragments; (blank) migrate away from each other; and (blank) assemble.
2. (blank) chromosomes undergo (blank) to form bivalents; (blank) may occur at this time in
which case sister chromatids are no longer identical.
3. (blank) condenses and (blank) become microscopically visible.
- Nuclear division is about to occur: nucleolus disappears; nuclear envelope fragments; centrosomes
migrate away from each other; and spindle fibers assemble. - Homologous chromosomes undergo synapsis to form bivalents; crossing-over may occur at this time in
which case sister chromatids are no longer identical. - Chromatin condenses and chromosomes become microscopically visible.
What happens in metaphase I?
1. Bivalents held together by (blank) have moved toward the metaphase plate at the equator of the spindle.
2. In metaphase I, there is a fully formed (blank) and alignment of the (blank) the metaphase plate.
3. Kinetochores, protein complexes just outside the centromeres, attach to spindle fibers called (blank)
spindle fibers.
4. Bivalents independently align themselves at the metaphase (blank) of the spindle.
5. Maternal and paternal (blank) of each bivalent may be oriented toward either pole.
- Bivalents held together by chiasmata have moved toward the metaphase plate at the equator of the
spindle. - In metaphase I, there is a fully formed spindle and alignment of the bivalents at the metaphase plate.
- Kinetochores, protein complexes just outside the centromeres attach to spindle fibers called kinetochore
spindle fibers. - Bivalents independently align themselves at the metaphase plate of the spindle.
- Maternal and paternal homologues of each bivalent may be oriented toward either pole.
What happens in Anaphase I?
- The (blank) of each bivalent separate and move toward opposite poles.
- Each chromosome still has two (blank)
- The homologues of each bivalent separate and move toward opposite poles.
- Each chromosome still has two chromatids.
What happens in Telophase I?
- In (blank), this stage occurs at the end of meiosis I.
- When it occurs, the (blank) reforms and (blank) reappear.
- This phase may or may not be accompanied by (blank)
- In animals, this stage occurs at the end of meiosis I.
- When it occurs, the nuclear envelope reforms and nucleoli reappear.
- This phase may or may not be accompanied by cytokinesis
What is interkinesis?
Interkinesis between meiosis I and II is similar to the interphase between mitotic divisions; however, no DNA replication occurs (the chromosomes are already duplicated).
What happens in Meiosis II?
In meiosis II, the (blank) divide and (blank) (derived as sister chromatids) separate. No replication of (blank) is needed between meiosis I and II because chromosomes are already doubled (DNA replication occurred prior to meiosis I). b. Chromosomes in the four daughter cells have only one (blank). c. Counting the number of centromeres verifies that parent cells were (blank); each daughter cell is (blank). d. In the animal life cycle, daughter cells become (blank) that fuse during fertilization. (blank) restores the diploid number in cells.
In meiosis II, the centromeres divide and daughter chromosomes (derived as sister chromatids) separate. a. No replication of DNA is needed between meiosis I and II because chromosomes are already doubled (DNA replication occurred prior to meiosis I). b. Chromosomes in the four daughter cells have only one chromatid. c. Counting the number of centromeres verifies that parent cells were diploid; each daughter cell is haploid. d. In the animal life cycle, daughter cells become gametes that fuse during fertilization. .Fertilization restores the diploid number in cells.
During metaphase II, the (blank) number of chromosomes align at the metaphase plate.
haploid
During anaphase II, the (blank) separate at the centromeres; the two (blank) move toward the poles.
sister chromatids; daughter chromosomes
In Meiosis II, Due to crossing-over, each (blank) can contain chromosomes with different types of genes.
gamete
At the end of telophase II and cytokinesis, there are four (blank) cells.
In animals, the haploid cells mature and develop into (blank)
In plants, the daughter cells become (blank) and divide to produce a haploid generation; these haploid
cells fuse to become a (blank) that develops into a diploid generation.
haploid
gametes
spores
zygote
What is the alternation of generations?
The type of life cycle of alternating haploid and diploid generations
What is crossing-over? What does it introduce?
an exchange of genetic material between non-sister chromatids of a bivalent; this introduces variation.
At synapsis, homologous chromosomes are held in position by a nucleoprotein lattice called (blank) The lattice holds the (blank) together so that the DNA of the duplicated chromosomes of each homologue pair is aligned, then (blank) may occur.
As the lattice of the synaptonemal complex breaks down, homologues are temporarily held together by (blank) regions where the (blank) chromatids are attached due to DNA strand exchange and crossing-over
The (blank) separate and are distributed to daughter cells.
Due to this genetic (blank), daughter chromosomes derived from sister chromatids are no longer identical.
(the synaptonemal complex). bivalents; crossing-over
chiasmata, non-sister, homologues, recombination
In males, meiosis is part of (blank) (the production of sperm), and occurs in the (blank)
spermatogenesis; testes
In females, meiosis is part of (blank) (the production of eggs), and occurs in the (blank)
oogenesis; ovaries
- Spermatogenesis
a. In the testes of males, primary (blank) with (blank) chromosomes undergo meiosis I to form two secondary (blank) , each with (blank) duplicated chromosomes.
b. Secondary (blank) divide (meiosis II) to produce four (blank), also with (blank) daughter
chromosomes.
c. Spermatids then differentiate into (blank) (spermatozoa).
d. Meiotic cell division in males always results in (blank) cells that become sperm.
Immature sperm is? Mature sperm is?
a. spermatocytes; 46; spermatocytes; 23
b. spermatocytes; spermatids; 23
c. sperm
d. four
spermatocyte; spermatid
- Oogenesis
a. In the ovaries of human females, primary (blank) with (blank) chromosomes undergo meiosis I to form
two cells, each with (blank) duplicated chromosomes.
b. One of the cells, a secondary (blank) receives almost all the cytoplasm; the other cell, (blank), disintegrates or divides again.
c. The secondary (blank) begins meiosis II and then stops at metaphase II.
d. At (blank), the secondary (blank) leaves the ovary and enters an (blank) where it may meet a
sper
e. If a (blank) enters the secondary (blank), it is activated to continue meiosis II to completion;
the result is a (blank) and another (blank), each with (blank) daughter chromosomes.
f. Meiosis produces one (blank) and three (blank); (blank) serve to discard unnecessary chromosomes and retain most of the cytoplasm in the egg.
g. The cytoplasm serves as a source of nutrients for the developing (blank)
a. oocytes; 46; 23
b. oocyte; a polar body
c. oocyte;
d. ovulation; oocyte; oviduct
e. sperm; oocyte; mature egg; polar body; 23
f. egg; polar bodies; polar bodies
g. embryo
In plants, there are two adult stages: one is diploid (called the (blank)) and one is haploid (called the (blank)).
sporophyte; gametophyte
What did Gregor Mendel do?
he was an Australian monk who formulated two fundamental laws of heredity in the early 1860s. Mendel’s particulate theory is based on the existence of minute particles—now called genes.
What did Gregor Mendel do with garden peas? Why did he choose them?
b. From many varieties, Mendel chose 22 (blank) varieties for his experiments.
c. (blank) varieties had all offspring like the parents and like each other.
d. Mendel studied simple (blank) e.g., seed shape and color, flower color, etc.).
2. He used his understanding of (blank) to interpret his results.
He chose the garden pea, Pisum sativum, because peas were easy to cultivate, had a short generation time, and could be cross-pollinated by hand.
b. From many varieties, Mendel chose 22 true-breeding varieties for his experiments.
c. True-breeding varieties had all offspring like the parents and like each other.
d. Mendel studied simple traits (e.g., seed shape and color, flower color, etc.).
2. He used his understanding of mathematical principles of probability to interpret his results.
How did Gregor Mendel cross-pollinate?
He performed reciprocal crosses, i.e., pollen of tall plant to stigma of short plant and vice versa. cross-pollinated by hand. Pollen was transferred from the male (anther) of one plant to the female (stigma) parts of another plant. Cut away anthers and brushed on pollen from another plant.
Mendel confirmed that his tall plants always had tall offspring, i.e., were true-breeding, before what
before crossing two different strains that differed in only one trait
Mendel tracked each trait through two generations.
a. P generation is the (blank) generation in a breeding experiment.
b. F 1 generation is the (blank) offspring in a breeding experiment.
c. F 2 generation is the (blank) offspring in a breeding experiment
parental
first generation
second generation
Characteristics of other parents reappeared in about 1/4 of F 2 plants; 3/4 of offspring resembled the F 1 plants.
Mendel saw that these 3:1 results were possible if:
factors separated when gametes were formed; a gamete carried one copy of each factor and random fusion of all possible gametes occurred upon fertilization.
What does homozygous mean?
two identical alleles for a trait. Homozygous dominant genotypes possess two dominant alleles for a trait. Homozygous recessive genotypes possess two recessive alleles for a trait.
What does heterozygous mean?
possess one of each allele for a particular trait.
What is a phenotype?
Phenotype refers to the physical appearance of the individual (tall, short, etc.).
What is a genotype?
Genotype refers to the alleles an individual receives at fertilization (dominant, recessive).
