Cell Cycle Flashcards
In human cells, there are ___ chromosomes
46
There are ___ homologous pairs, called the autosomes
22
There are ___ sex chromosomes
2
___ is the female sex chromosomes
XX
___ is the male sex chromosomes
XY
Germ cells or sex cells consist of __ & __?
Sperm &
Oocyte (ovum)
Non-germ cells are called?
Somatic cells
The sequence of events that controls cell growth and division is called?
Cell cycle
The period of time it takes for a cell to complete one cell division is called?
Cell cycle
The cell cycle is divided into four phases namely?
G0
Gap 1(G1)
Synthesis (S)
Gap 2(G2)
How many checkpoints are in the cell cycle?
Three
The G1/S checkpoint ensures?
Cell nutrition, size and environment are favourable
DNA is intact
G2/M checkpoint ensures?
DNA is completely replicated
Metaphase/Anaphase checkpoint ensures?
DNA is intact
Chromosomes are attached to the mitotic spindle
The G1/S checkpoint prepares for?
DNA replication and entering of S phase
G2/M checkpoint prepares the cell for?
Mitosis
Metaphase/Anaphase checkpoint prepares?
Cytokinesis
G1, S & G2 phases are collectively referred to as?
Interface
Three characteristics of G1 phase are?
Longest part of the cycle
Active RNA & protein synthesis
Cell volume is restored to its original size
Three properties of S phase are?
DNA replication
Histone synthesis
Centrosome duplication
One property of G2 phase is?
Proteins required for mitosis accumulate
Three properties of G0 phase are?
Prolonged non-dividing phase
Differentiated & specialized cells
Temporarily or permanently suspended cell cycle activities
The cell cycle checkpoints are regulated by cytoplasmic proteins called?
Cyclins
Cyclins activate?
Cyclin-dependent kinases(CDK’s)
CDK’s initiate/induce progression through the?
Cell cycle
Progression through the cell cycle is halted by adverse conditions like?
Inadequate nutrition
Inappropriate cellular microenvironments
DNA damage
Somatic reproduction of cells is called?
Mitosis
Mitosis includes?
Segregation of replicated chromosomes
Nucleus division(karyokinesis)
Cytoplasm division (cytokinesis)
Production of two identical daughter cells
The events of mitosis are subdivided into 5 major stages namely
Prophase Prometaphase Metaphase Anaphase Telophase
In prophase?
Centrioles move apart
Spindle forms
Nucleolus disappears
Kinetochores develop at centromeres of each chromatid
In prometaphase?
Mitotic spindle moves into nuclear area
Nuclear membrane disappears
Each duplicated chromosome becomes attached at the kinetochore
In metaphase?
Chromosomes condense further
Kinetochores at each centromere attach to the mitotic spindle
Chromosomes align themselves at the cell equator
In Anaphase?
Spindle poles move further move apart
Microtubules lengths changes
Sister chromatids separate and are pulled towards opposite spindle poles
In telophase?
Nuclear membrane forms
Centrioles duplicate
Nucleoli reappear
Chromosomes decondense
Slowly dividing population of cells that serve to renew the differentiated cells of tissues are called?
Stem cells
Stem cells divide ___?
Asymmetrically
Stem cells produce one cell that remains as a ____ and another cell that differentiates into a ____
Stem cell
Progenitor cell
Progenitor cells are also called?
Transit amplifying cells
Embryonic stem cells are theoretically?
Totipotent(able to differentiate into any other cell type)
Stem cells found in adults are either____ or ____
Multipotent(produce cells of several lineages) Eg multipotent haematopoietic stem cells produce all blood formed elements
Unipotent( produce a single cell type) eg unipotent epidermal stem cells produce epithelial cells
A special form of cell division in germ cells in which the chromosome number is reduced from Diploid (2n) to haploid (n) is called?
Meiosis
Meiosis involves two successive cell divisions namely?
Meiosis 1
Meiosis 2
The cell resulting from meiosis differs from other cells in?
Number of chromosomes is reduced to half
Genetic information isn’t identical
Prophase 1 is divided into 5 stages namely?
Leptotene Zygotene Pachytene Diplotene Diakinesis
In prophase 1?
Chromatin condenses into visible chromosomes
Each chromosome consists of two chromatids joined at the centromere
Homologous maternal and paternal chromosomes pair form a tetrad
Nucleolus and nuclear envelope disappear
Crossing over occurs at the chiasmata
The random exchange of genes between homologous chromosome segments is called?
Crossing over
In metaphase 1?
Homologous pairs of chromosomes align at the cell equator
Spindle fibers from either pole attach to the kinetochore of any one of the chromosome pairs
In Anaphase 1?
Chromosomes migrate to poles
Chromatids separate
In telophase 1?
Nuclear envelope is re-established
Two daughter cells are formed
Each daughter cell contains 23 chromosomes (n)
Each chromosome is composed of two similar sister chromatids not genetically identical
Meiosis 2 properties are?
A brief interphase without DNA replication (no S phase)
Two daughter cells divide producing four daughter cells each with its own recombined genetic material
Mitosis has ____ of homologous chromosomes, meiosis has ____ of homologous chromosomes
no pairing
pairing
Mitosis occurs in only _____organisms, while meiosis occurs in _______of humans, animals, plants & fungi
All
Reproductive cells
Mitosis has only _____ cell division, meiosis has ____
One
Two
Mitosis has ____ diploid daughter cells, meiosis has ____ haploid cells
two
four
Mitosis reproduction type is _____ , meiosis is _____
asexual
sexual
Crossing over ____ in mitosis, crossing over ____ in meiosis
doesn’t occur
occurs
Mitosis produces _____ organisms or cells, meiosis produces _____ organisms or cells
identical
different
N + 1 = 24 and N - 1 =22 This describes a condition where members of a pair fail to separate resulting in one daughter cell having an extra chromosome and the other daughter cell at the opposite pole minus a chromosome. This is known as?
Nondisjunction of chromosomes
The resulting zygote upon fertilization with a normal gamete containing 23 chromosomes will have either____ or____
47 chromosomes (trisomy for that extra chromosome) 45 chromosomes (monosomy for the missing chromosome)
Which Chromosomes are usually affected by chromosome nondisjunction?
8 9 13 18 21
Defects caused by chromosome nondisjunction are?
Down syndrome(trisomy 21) Klinefelter syndrome(XXY)
Down syndrome(trisomy 21) is characterized by?
Mental retardation
Short stature
Congenital heart malformations
Klinefelter syndrome(XXY) is characterized by?
Infertility
Variable degrees of masculinazation
Small testes
The presence of an abnormal number of chromosomes in a cell is called?
Aneuploidy
The process of pairing and ordering all the chromosomes of an organism, thus providing a genome-wide snapshot of an individual’s chromosomes is called?
Karyotyping
The chromosome characteristics of an individual cell is known as?
Karyotype
Karyotypes provide information about the___&___ of an organisms chromosomes
Number
Morphology
