Lec 7 - Cell Cycle Flashcards
Why is cell reproduction important? (3 main reasons)
- Development from a fertilized cell
- Growth
- Repair
What is an integral part of the cell cycle, the life of a cell from formation to its own division?
Cell division
a special type of division that can produce sperm and egg cells
Meiosis
All the DNA in a cell constitutes the cell’s ______
genome
______ can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells
genome
Where are the DNA molecules packacged?
Chromosomes
Eukaryotic chromosomes consist of ______, a complex of DNA and protein that condenses during cell division
chromatin
What cells (non-reproductive cells) have two sets of chromosomes?
somatic cells
_______reproductive cells: sperm and eggs have half as many chromosomes as somatic cells
gametes
What is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached?
centromere
What are the two phases of cell cycle?
Mitotic (M) phase (mitosis & cytokinesis) and Interphase (cell growth & copying of chromosomes)
It is about 90% of the cell cycle and can be divided into 3 subphases
Interphase
What are the three subphases of interphase ?
G1 phase (“first gap”)
S phase (“synthesis”)
G2 phase (“second gap”)
The cell grows during all three phases, but chromosomes are duplicated only during the _____
S phase
What are the 5 stages of Mitosis?
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
What is a structure made of microtubules that controls chromosome movement during mitosis?
mitotic spindle
The spindle includes the ______, the ________ , and the _______
centrosomes, the spindle microtubules, and the asters
In animal cells, cytokinesis occurs by a process known as _____, forming a cleavage furrow.
cleavage
In animal animal cells, a cleavage furrow is formed during cytokinesis but how about in plant cells?
cell plate
Prokaryotes (bacteria and archaea) reproduce by a type of cell division called?
Binary fission
In this process,
the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart
binary fission
It is in this checkpoint that is very important to move to other phases.
G1 checkpoint
If the cell does not receive the go-ahead signal from G1, it will exit the cycle, switching into a non-dividing state called?
G0 phase
What are the two types of regulatory proteins that are involved in cell cycle control?
cyclins and cyclin-dependent kinases (Cdks)
What is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase?
MPF (maturation-promoting factor)
Examples of internal and external signals:
Internal: kinetochores not attached to spindle microtubules
External: growth factors
A clear example of external signals is ____________, in which crowded cells stop dividing
density-dependent inhibition
Most animal cells also exhibit _________, in which they must be attached to a substratum in order to divide
anchorage dependence
True or False: Cancer cells exhibit neither density-dependent inhibition nor anchorage dependence
True
These cells may not need growth factors to grow and divide. They may make their own growth factor
They may convey a growth factor’s signal without the presence of the growth factor They may have an abnormal cell cycle control system
Cancer cells
A normal cell is converted to a cancerous cell by a process called ________
Transformation
If abnormal cells remain only at the original site:____
Benign tumors
If abnormal cells invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional tumors
Malignant tumors
What are the units of heredity, and are made up of segments of DNA?
Genes
Genes are passed to the next generation via reproductive cells called?
Gametes (sperm and eggs)
In this type of reproduction, single individual passes genes to its offspring without the fusion of gametes.
Asexual reproduction
What do you call a group of genetically identical individuals from the same parent?
Clone
In this type of reproduction, two parents give rise to offspring that have unique combinations of genes inherited from the two parents
Sexual reproduction
What is the generation-to-
generation sequence of stages in the
reproductive history of an organism?
Life cycle
What is an ordered display of the pairs of chromosomes from a cell?
Karyotype
Human somatic cells have how many pairs of chromosomes?
23 pairs
What determine the sex of the individual, are called X and Y.
Sex chromosomes
Homologous pair for female and male?
Female: X X chromosomes
Male: X Y chromosomes
The remaining 22 pairs of chromosomes are called?
Autosomes
A ______cell (2n) has two sets of chromosomes
diploid
2 x 23 = 46
What are the two stages of Meiosis?
Meiosis I (reductional division)
and
Meiosis II (equational division)
In this stage of meiosis, sister chromatids separate
Meiosis II (equational division)
In this stage of meiosis, homologs pair up and separate, resulting in two haploid daughter cells with replicated chromosomes
Meiosis I (reductional division)
What reduces the number of chromosomes sets from two (diploid) to one (haploid), producing cells that differ genetically from each other and from the parent cell
Meiosis
What conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell
Mitosis
Occurs when the chromosomes fail to separate properly as the cell divides
Nondisjunction
XXY condition Results mainly from nondisjunction in mother (67%)
Phenotype is tall males. Sterile or nearly so.
Feminized traits (sparse facial hair, somewhat enlarged breasts) Treated with testosterone injections
Klinefelter’s Syndrome
Trisomy of chromosome 21, Mental impairment and a variety of additional defects
Down’s Syndrome
Inheritance of only one X (XO) 98% spontaneously aborted. Survivors are short, infertile females. No functional ovaries
Secondary sexual traits reduced May be treated with hormones, surgery
Turner’s syndrome
What are the sources of genetic variability?
- Independent assortment
- Random fertilization
- Crossing-over
