2: GENETIC BACKGROUND OF DEVELOPMENT Flashcards
1
Q
a slender material inside the nucleus, usually found as colored
bodies during cell division.
A
Chromosome
2
Q
Each chromosome is composed of ____ which separate during cell
division
A
sister chromatids
3
Q
has a ____ or primary constriction (“waist line”), where the
kinetochore proteins are attached.
A
centromere
4
Q
____ the sight of attachment of spindle fibers. The tip of the
chromosome arm, needed for chromosome stability, is called ____.
A
Kinetochore
telomeres
5
Q
centromere is at the middle part of the chromosome
A
Metacentric
6
Q
centromere is sub-median; (near the middle); long-up & short-down
A
Sub-metacentric
7
Q
centromere is at the subterminal portion; (3/4 at tip of chromosome);
short-up & long-down
A
Acrocentric
8
Q
centromere is at the terminal end of the chromosome
A
Telocentric
9
Q
A sexually reproducing individuals possess ____, one
set coming from the male and another set coming from the female parent
A
two sets of chromosomes (2n)
10
Q
complete set of chromosomes coming from either parent
A
Genome
11
Q
Each of the chromosome in a genome has corresponding ____
A
identical
chromosomes or homologue.
12
Q
Each ____ divides once the cell divides. This is accomplished through
cell division.
A
chromosome
13
Q
continuity of life is based upon the reproduction of cells
A
cell division.
14
Q
CELL DIVISION purpose
A
- multicellular organism to grow and
- reach the adult size,
- replaces worn-out or damaged cells, and
- keeps the total number of cells in an adult organism relatively constant.
15
Q
The Key Roles of Cell Division
A
- unicellular organisms reproduce by cell division
- necessary for the repair and renewal of the worn-out tissues
- for the formation of new cells
- for cell growth, development and tissue differentiation
16
Q
involved in in the distribution of the identical genetic materials
(DNA) to two daughter cells
A
Cell division
17
Q
The genes are located in a
____ that is found in the nucleus
A
chromosome
Chromosomes are greatly involved in cell
division and in the reproductive process of an organism.
18
Q
series of stages in the life of the cell is referred to as
A
cell cycle.
19
Q
referred to as the “preparatory stage”
A
Interphase
20
Q
▪ it is the longest phase in the cell cycle for most cells
▪ typically, it lasts for at least 90% of the total time required for the cell cycle
A
Interphase
21
Q
a cell at interphase may appear resting under the microscope but it actually goes
through a period of ____
A
very high metabolic activity
22
Q
- grow in size; cell increases in volume
- cell is preparing the chemicals necessary for DNA synthesis
- ER, golgi apparatus, ribosomes, mitochondria and chloroplast are
formed - chromatin, although it would appear as darkly staining materials, if
stretched would resemble a long chromatin fiber
A
G1 phase (first growth phase)
23
Q
- each of the chromosomes is replicated by the cell
- where DNA synthesis or replication occurs
A
S phase (DNA synthesis)
24
Q
- cell “double checks” the duplicated chromosomes for error, making any
needed repairs - active synthesis of RNA and proteins (needed for synthesis of
chromosomes) - formation of mitotic spindle occurs
- doubled chromatin fiber folds to form a chromosome
- continue until the onset of mitosis
A
G2 phase (second growth phase)
25
the period of nuclear division and cytokinesis
M-phase (Mitotic phase)
26
the actual division
of the cytoplasm and generation of two new daughter cells
cytokinesis
27
series of events wherein each cell divides to form to new daughter cells which
are exactly identical to the mother cell
Mitosis
28
division of the nucleus, with its contents (duplicated chromosomes: 2n), into
two identical nuclei
Mitosis
29
mitosis occurs in ____ except sex cells or gametes
body or somatic cell and other cells
30
- Chromatin in the nucleus begins to condense and becomes visible in
the light microscope and now called chromosomes
- Chromosomes are thickened and become shortened
- Centrioles begin moving to the opposite ends of the cell
- Fibers extend from the centromeres. Some fibers cross the cell to form
mitotic spindle
- Nucleoli and nuclear membrane completely disappear
Prophase
31
- The chromosomes move along the middle of the cell to ensure that the
next phase, when they separate, each nucleus will receive one copy of
each chromosome
- Centrioles reached the opposite end of the nucleus
- Chromosomes become attached to the spindle fibers and move toward
the equator
- Chromosomes tightly coiled and discrete; it is very much condensed
Metaphase
32
- At early anaphase, centromeres are duplicated and start moving apart;
sister chromatids start to separate
- At late anaphase, two identical sets of chromosomes move toward the
opposite poles and spindle begins to disappear
Anaphase
33
- Chromatids arrive at the opposite poles of the cell
- Chromosomes in their respective poles become enclosed in a nuclear
membrane
- Chromosomes begin to thin out, uncoil, and no longer visible;
- Spindle fibers disperse and cytokinesis may also begin during this
stage
Telophase
34
In plant tissues – the cytoplasm is divided via ____ where
separation starts from the inside of the cell towards the periphery
cell plate formation
35
▪ In animal tissues - cell cytokinesis occurs via ____
formation starting from the periphery
furrowing or cleavage
36
process by which gametes are generated for reproduction
Meiosis
37
meiosis occurs during ____, the whole process involved in gamete
formation
gametogenesis
38
the chromosome number turns to half (n)
Meiosis
39
**reductional division**; involves the separation of
homologous chromosomes resulting in two cells with haploid (n)
chromosome number
Meiosis I
40
**equational division**; the two haploid cells proceed to the
second division involving only the separation of chromatids producing
four haploid cells
Meiosis II
41
Chromosomes appear as long thin threads with many
bead-like structures (chromomeres) along their length.
Leptotene
42
Synapsis or pairing of homologous chromosomes begins.
The paired chromosomes form a bivalent consisting of
four (4) chromatids.
Zygotene
43
. Chromosomes are thicker due to further coiling.
- Chromatid breaks and their repair occur along the
chromosome.
- Repairing of breaks may entail exchange of segments
between sister and non-sister chromatids in a bivalent
and this is known as crossing over
Pachytene
44
The longitudinal separation of homologues in a bivalent
starts from the centromere and proceeds towards ends
Diplotene
45
Bivalents are maximally condensed and distributed
throughout the nucleus.
- Nucleolus and nuclear membrane disappeared, the
spindle has formed and Prophase I is completed
Diakinesis
46
- The bivalents align at the metaphase/equatorial plane.
- Centromeres attached to the spindle fibers
Metaphase I
47
- Univalents in each bivalent separate from each other, thus,
each anaphase group is composed of a haploid number (n)
of chromosomes
Anaphase I
48
- Chromosomes regroup and their coiled structures begin to
relax
Telophase I
49
In some species, no cytokinesis happens after Meiosis I. a
brief transitional stage called ____ occurs before the cell proceeds to the next
stage
interkinesis
50
meiosis II starts with ____
haploid cells
51
At the end of the meiosis, four new daughter cells are produced, each with a ____ number of chromosomes
diploid
52
– similar to mitotic prophase except that it contains haploid
chromosomes
Prophase II
53
- Formation of new spindle fibers; chromosomes aligned at the metaphase plate
Metaphase II
54
- Daughter chromosomes move toward the opposite poles
Anaphase II
55
- Reappearance of nucleolus and nuclear membrane; formation of four (4) haploid daughter cells
Telophase II
56
Cytokinesis follows (after meiosis II), forming four cells with ____ chromosome number.
haploid (n)
## Footnote
Meiosis may not always proceed normally. Some errors may occur affecting the
functioning of the spindle fibers of the movement of the chromosome.
57
The sequential events of the cell are directed by a distinct ____
Cell Cycle Control
## Footnote
The clock has specific checkpoints where the cell cycle stops until a go-ahead
signal is received
58
Two types of regulatory proteins are involved in cell cycle control:
cyclins and
cyclin-dependent kinases (Cdks)
59
# Barresi and Gilbert
each somatic cell nucleus has the same chromosomes—and therefore the same set of genes—as all other somatic cell nuclei - known as ____
genomic
equivalence.
60
# cell differentiation
selective production of different proteins within cells creates
cellular diversity
61
as the single-celled zygote divides to start the generation of all the cells making up an organism, differences in the expression of genes in these cells ____
govern maturation toward distinct cell types
62
many regulatory mechanisms ____ lead to this differential
gene expression
* targeting DNA access,
* RNA production and processing, and
* protein synthesis and modification
63
a process in which based on the unique combination of genes that are active, or “expressed”, cells become different from one another
Differential Gene Expression
64
a process by which cells become specialized and take on specific roles in an organism
Differential Gene Expression
## Footnote
By expressing different genes, cells can create different
proteins that lead to the differentiation of cell types
65
Three Postulates of Differential Gene Expression
1. Every somatic cell nucleus of an organism contains the complete genome
established in the fertilized egg. The DNA of all differentiated cells is
identical.
2. The unused genes in differentiated cells are neither destroyed nor mutated;
they retain the potential for being expressed.
3. Only a small percentage of the genome is expressed in each cell, and a portion
of the RNA synthesized in each cell is specific for that cell type.
66
gene expression can be regulated at four
levels:
1. Level 1: Differential gene transcription
2. Level 2: Selective pre-messenger RNA processing
3. Level 3: Selective messenger RNA translation
4. Level 4: Differential posttranslational protein modification
67
regulates which proteins are allowed to remain and/or function in the cell
Level 4: Differential posttranslational protein modification
68
regulates which of the mRNAs in the cytoplasm are translated into proteins.
. Level 3: Selective messenger RNA translation
69
regulates which parts of the transcribed RNAs are able to enter the cytoplasm and become messenger RNAs.
. Level 2: Selective pre-messenger RNA processing
70
Level 1: Differential gene transcription
regulates which of the nuclear genes
are transcribed into pre-messenger RNA.
71
sequence of events that enables the use and transfer of information to make the proteins of a cell
Central Dogma
72
central to this theory is the ____ in double-stranded DNA, which provides the informative code or blueprints (for the precise combination of amino acids needed to build specific proteins)
order of deoxyribonucleotides
73
Proteins are not made directly from DNA, however; rather, the sequence of DNA bases is first copied, or transcribed, into a single-stranded polymer of similar molecules called ____, more commonly known as pre-mRNA.
heterogeneous nuclear ribonucleic acids (hnRNA)
74
the process of copying DNA into RNA
Transcription
75
RNA produced from a given gene is often referred to as a
transcript
76
although the transcribed pre-mRNA includes the sequences to code for a protein, it can also hold ____
non-protein-coding (simply called noncoding)
information
77
the pre-mRNA strand will undergo processing to excise the noncoding domains and protect the ends of the strand to yield a
messenger RNA (mRNA)
molecule
78
mRNA is transported out of the nucleus into the cytoplasm where it can
interact with a ribosome and present its message for the ____
synthesis of a specific
protein
79
▪ mRNA unveils the complementary sequence of DNA three bases at a time
▪ each triplet, or codon, calls for a ____ that will be covalently
attached to its neighboring amino acid denoted by the codon next in line
specific amino acid
80
leads to the synthesis of a polypeptide chain that will undergo protein folding and potential modification by the addition of various functional moieties, such as carbohydrates, phosphates, or cholesterol groups
Translation
81
The completed protein is now ready to carry out its specific function serving to support the ____ properties of the cell.
structural or functional
## Footnote
Cells that express different proteins will therefore possess different structural and functional properties, making them distinct types of cells
