Biology: Concepts and Connections, 7th Edition, Chapter 8
Chiasma
(greek for cross) The sites of crossing over appear as X-shaped regions. A place where two homologous (non sister) chromatids are attached to each other.
Locus
(plural- loci) A particular place on the chromosome
In metaphase of mitosis, each chromosome contains how many chromatids?
2 sister chromatids
The haploid number for humans is
23, n=23
A human cell at metaphase contains how many sets of duplicated chromosomes?
23, they occur in matched pairs
The total number of combinations of chromosomes that meiosis can package into gametes for any species is
2^n, n=haploid number
For humans the diploid number is
46, 2n=46
Researchers have discovered how many different types of growth factors that can trigger cell division?
50
In humans, 46 chromosomes is equal to how many chromatids?
92 chromatids
The cell plate grows
Outward
Which of the following statements regarding prokaryotes is false?
Prokaryotic chromosomes are more complex than those of eukaryotes
Crossing over begins very early in what phase of meiosis?
Prophase I
Duplicated homologous chromosomes pair to form tetrads in what phase?
Prophase I
The five stages of mitosis
Prophase, prometaphase, metaphase, anaphase, telophase
Cell division
Reproduction at the cellular level, requires the duplication of chromosomes, and sorts new sets of chromosomes into the resulting pair of daughter cells.
What function does cell division play in an amoeba? In your body?
Reproduction; Growth, development, and repair.
Sexual Reproduction
Requires fertilization of an egg by a sperm. Testes and ovaries. Takes half of the genes from both parents.Not Identical.
Chromosomes duplicate in which sub phase?
S phase
Tetrads
Sets of four chromatids, with each pair of sister chromatids joined at the centromeres
Vascular endothelial growth factor (VEGF)
Stimulates the growth of new blood vessels during fetal development and after injury
Homologous chromosomes come together as pairs in a process
Synapsis, In prophase I
The S in S phase stands for what?
Synthesis of DNA, or DNA replication
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
Telophase I
Autosomes
The 22 remaining pairs of chromosomes found in males and females.
Translocation
The attachment of a chromosomal fragment to a non homologous chromosome. May be reciprocal: two non homologous chromosomes may exchange segments
Trisomy 21
The basis of Down syndrome
What cycle multiplies cells?
The cell cycle
Telophase
The cell elongation that started in the anaphase continues. Daughter nuclei appear at the two poles of the cell as nuclear envelopes from around the chromosomes. The reverse of prophase
What happens in all three sub phases of the interphase stage?
The cell grows.
The total number of chromosomes is called
The diploid number (2n)
Metaphase
The mitotic spindle is fully formed, poles at opposite ends. Chromosomes convene on the metaphase plate, an imaginary plane equidistant between the two poles of the spindle.
Prometaphase
The nuclear envelope breaks into fragments and disappears. Microtubules are now highly condensed. Centromere region, each sister chromatid have protein structure called a kinetochores.
Meiosis
The production of egg and sperm cells involves a special type of cell division. Produces haploid gametes in diploid organisms
Genetic Recombinant
The production of gene combinations different from those carried by the original parental chromosomes.
Life cycle
The sequence of stages leading from the adults of one generation to the adults of the next.
Cleavage furrow
a shallow indentation in the cell surface
With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have
a similar but not identical combination of genes.
Tumor
an abnormally growing mass of body cells
Karyotypes
are often produced from dividing cells arrested at metaphase of mitosis
Sarcomas
arise in tissues that support the body (bone, muscle)
Strictly speaking, the phrase "like begets like" refers to
asexual reproduction only
When the cell cycle operates normally, mitosis produces genetically identical cells for
growth, replacement of damaged and lost cells, and asexual reproduction.
Because in meiosis, one duplication of chromosomes is followed by two divisions, each of the four daughter cells produced
has a haploid set of chromosomes and are not genetically identical
Chronic myelogenous leukemia (CML)
is one of the most common leukemias,affects cells that give rise to white blood cells (leukocytes), and results from part of chromosome 22 switching places with a small fragment from a tip of chromosome 9.
Nondisjunction can happen if
meiosis I, if both members of a homologous pair go to one pole or meiosis II if both sister chromatids go to one pole.
In meiosis, how many crossover events occur per chromosome pair?
one to three
During _____ a spindle forms in a haploid cell.
prophase I
Cytokinesis
Begins before mitosis ends, the cytoplasm is divided into two. Occurs along with Telophase.
Anaphase
Begins when the two centromeres of each chromosome come apart, separating the sister chomatids. Chromatids consider full fledged daughter chromosome.
Prokaryotes reproduce by a cell division called
Binary Fission
Alterations of chromosome structure can cause
Birth defects and cancer
Malignant Tumor
Can spread into neighboring tissues and other parts of the body, displacing normal tissue and interrupting organ function as it goes
An individual with a malignant tumor is said to have
Cancer
Leukemias and Lymphomas
Cancers of blood-forming tissues (bone marrow, spleen, lymph nodes
Carcinomas
Cancers that originate in the external or internal coverings of the body (skin, lining of the intestine)
Based on site of origin, cancers are grouped into four categories.
Carcinomas, Sarcomas, Leukemias, and Lymphomas
The process of cell division is a key component of the
Cell cycle
The spindle microtubules emerge from two
Centrosomes
The site of attachment and crossing over.
Chiasma, Nonsister chromosomes join here
Homologous Chromosomes
Chromosomes that have twins resembling its length and centromere position. Two chromosomes of matching pairs both carrying genes controlling the same inherited characteristics.
In animal cells, cytokinesis occurs by a process known as
Cleavage
The first sign of cleavage is the appearance of
Cleavage furrow
Centrosomes
Clouds of cytoplasmic material that in animal cells contain pairs of centrioles. (Microtubule-organizing centers)
As a cell prepares to divide its chromatin
Coils up
Asexual reproduction
Creation of genetically identical offspring by a single parent. (ex. Sea star species). Lone parent and each offspring have have identical genes.
Nonsister chromatids exchange genetic material in a process
Crossing over
Which of the following statements regarding the differences between mitosis and meiosis is false?
Crossing over is a phenomenon that creates genetic diversity during mitosis.
The sources of genetic variability therefore include
Crossing over, Independent orientation of chromosomes, and Random fertilization
Chromatin
DNA in its loose state. DNA in one cell would exceed my own height.
Cells in the human liver do not divide unless the liver is
Damaged
If a fragment of a chromosome is lost or removed, the remaining chromosome will then have a ______.
Deletion
Turner syndrome
Denoted as XO, Lacking one X chromosome, Are females and sterile because their sex organs are underdeveloped. Individuals usually have a short statue and a web of skin between the neck and shoulders
Klinefelter syndrome
Denoted as XXY, Have a extra X chromosome, Individuals are males, but testes are abnormally small and individuals are sterile. Often includes breast enlargement, and other female body characteristics
Sex Chromosomes
Determines an individual's sex
If a fragment from one chromosome joins to a sister chromatid or homologous chromosome, it will produce a ______
Duplication
Cell plate
During telophase, in plant cells, membranous vehicles containing cell wall material collect at the middle of the parent cell. The vesicles fuse forming a membranous disk.
Sister Chromatids
Each chromosome that consist of two copies of DNA molecules, Creating daughter cells.
What gender has fully homologous chromosomes?
Females (XX)
In a living animal, most cells are anchored in a _____ position.
Fixed
Interphase can be divided into three sub phases.
G1 phase (First gap), S phase, G2 phase (second gap)
What are the three major checkpoints in a cell cycle?
G1, G2, M
At which one of the three checkpoints do the chromosomes exist as duplicated sister chromatids?
G2 and M checkpoints
Each _____ has a single set of chromosomes, 22 autosomes plus a sex chromosome. (X or Y)
Gamete
_____ are made by a special sort of cell division called _____, which occurs only in reproductive organs.
Gametes, Meiosis
Which of the following statements regarding genetic diversity is false?
Genetic diversity is enhanced by mitosis.
Each daughter cell produced by meiosis II has only one ______ set of chromosomes.
Haploid
What type of chromosome pairs have different versions of the same gene?
Homologous
Diploid
Humans, animals, many plants are considered this because all body cells contain pairs of homologous chromosomes.
How are chromosomes matched?
In homologous pairs
Somatic cell
In humans, a typical body cell that has 46 chromosomes
Genetic variation in gametes results from
Independent orientation at metaphase I and random fertilization.
Three sources of genetic variability in sexually reproducing organisms
Independent orientation of chromosomes at metaphase I, random fertilization, and crossing over during prophase I or meiosis.
The time when a cell's metabolic activity is very high and the cell performs its various functions with the organism.
Interphase, or growing stage
Most of the cell cycle is spent in what stage?
Interphase, or growing stage about 90% of the time
If a fragment reattaches to the original chromosome but in the reverse orientation.
Inversion
f a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n)
Inversion
What type of blood cell is used to prepare a karyotype?
Lymphocytes
Mitotic phase
M phase, The part of the cell cycle when the cell actually divides. Accounts for 10% of the total time required for the cell cycle.
Chromosomes X and Y behave as a homologous pair in
Meiosis
_____ prevents each generation from having twice as much genetic material as the generation before
Meiosis
_____ reduces the chromosome number from diploid to haploid.
Meiosis
All events unique to meiosis happens in
Meiosis I
A human in what phase contains 23 sets of duplicated chromosomes.
Metaphase
All the chromosome pairs orient independently at what phase?
Metaphase I
Tetrads align at the cell equator in which phase?
Metaphase I
Tetrads are aligned at the metaphase plate in what phase?
Metaphase I
During _____ chromosomes align single file along the equator of a haploid cell.
Metaphase II
Meiosis II is virtually identical to _____ because the separate sister chromatids
Mitosis
_____ produce daughter cells with the same number of chromosomes as the parent cells, _____ reduces the chromosome number by half.
Mitosis, meiosis.
What phase is divided into two overlapping stages? What are the stages?
Mitotic phase. Mitosis and Cytokinesis
XXX
Most are normal females with an extra X chromosome
XYY
Most are normal males with an extra Y chromosome (although they tend to be taller than average)
Whats ultimately responsible for genetic diversity in living organisms?
Mutations
Haploid
A cell with a single chromosome set; has only one member of each homologous pair.
The Cell Cycle Control System
A cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle.
Mitotic Spindle
A football-shaped structure of microtubules that guides the separation of the two sets of daughter chromosomes
The cell cycle consist of two main stages.
A growing stage (interphase) and the actual cell division (mitotic phase)
Benign Tumor
A lump of abnormal cells that remain at the original site. Can be removed by surgery.
Density-dependent inhibition
A phenomenon in which crowded cells stop dividing.
Karyotype
A photographic inventory of an individual's chromosomes arranged in pairs. Shows them condensed and doubled as appeared in metaphase of mitosis
Mitosis
A process, The type of cell division responsible for asexual reproduction and for the growth and maintenance of multicellular organisms.
Growth factor
A protein secreted by certain body cell that stimulates other cells to divide
Hydra
A tiny multicellular animal that reproduces by either sexual or asexual means
How are cancers named?
According to the organ or tissue in which they originate.
These proteins responsible of muscle contraction are
Actin and Myosin
Crossing over
An exchange of corresponding segments between nonsister chromatids of homologous chromosomes
Nondisjunction
An occasional mishap in which the members of a chromosome pair fail to separate.
Cell cycle
An ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division into two cells
Homologous chromosomes migrate to opposite poles during _____.
Anaphase I
Pairs of homologous chromosomes separate, sister chromatids of each chromosome stay together in what phase?
Anaphase I
Most animal cells exhibit _____ _____; they must be in contact with a solid surface. Ex inside of a culture dish or the extracellular matrix of a tissue to divide.
Anchorage Dependence
What factors affect cell division?
Anchorage, cell density, and chemical growth
Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?
The sequences are identical.
Gametes
The sperm and egg cells
Metastasis
The spread of cancer cells beyond their original site
Chromosomes
The structures that contain most of the cells DNA
Platelet-derived growth factor
This protein promotes the rapid growth of connective tissue cells that help seal the wound
, there is no chromosome duplication between the end of meiosis I and the beginning of meiosis II. T/F?
True
At the end of meiosis I, There are _____ cells, with each chromosome still having two _____ _____.
Two, sister chromatids
When does the abnormal behavior of a cancer cell begin?
When a normal cell is converted into a cancer cell
When does a chromosome consist of two identical chromatids?
When the cell is preparing to divide and has duplicated its chromosomes but before the duplicates actually separate.
Prophase
Within the nucleus, chromatin fibers become tightly coiled and folded. Cytoplasm, the mitotic spindle begins to form as microtubules rapidly grow out from the centrosomes, they begin to move away from each other
When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of
density-dependent inhibition.
In mitosis, the nucleus and its contents divide and are evenly distributed forming
two daughter nuclei
Interphase stage
when the cell roughly doubles everything in its cytoplasm and precisely replicates its chromosomal DNA
