C2: Genetic Background Flashcards
slender material inside the nucleus, usually found as colored bodies during cell division.
Chromosome
Each chromosome is composed of ___ which separate during cell division
sister chromatids
chromosomes has a __ or primary constriction (“waist line”), where the kinetochore proteins are attached
centromere
____ is the sight of attachment of spindle fibers. The tip of the chromosome arm, needed for chromosome stability, is called ___
Kinetochore; telomeres
Chromosomes are classified into types based on the position of the centromere: 4
Metacentric
Sub-metacentric
Acrocentric
Telocentric
centromere is at the middle part of the chromosome
Metacentric
centromere is sub-median; (near the middle); long-up & shortdown
Sub-metacentric
centromere is at the subterminal portion; (3/4 at tip of chromosome); short-up & long-down
Acrocentric
centromere is at the terminal end of the chromosome
Telocentric
– complete set of chromosomes coming from either parent
Genome
When cells divide, they go through an orderly series of events known as the
____.
cell cycle
cell cycle is usually divided into ___ and ___
interphase, mitosis
It enables 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.
Cell division
The Key Roles of Cell Division (4)
-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
An organism’s complete complement of genetic material is called its ___
genome
replication and distribution of so much DNA is manageable because the
DNA molecules are packaged into ___
chromosomes
The series of stages in the life of the cell is referred to as the ___
cell cycle.
referred to as the “preparatory stage”; the longest phase; lasts for at least 90% of the total time
Interphase
sub-phases of interphase: 3
G1 phase (first growth phase)
S phase (DNA synthesis)
G2 phase (second growth phase)
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
G1 phase
in this sub-phase of interphase:
• each of the chromosomes is replicated by the cell
• DNA synthesis or replication occurs
S phase (DNA synthesis)
-double checks” the duplicated chromosomes for error;
-active synthesis of RNA and protein;
-formation of mitotic spindle occurs;
-doubled chromatin fiber folds to form a chromosome
G2 phase (second growth phase)
period of nuclear division and cytokinesis .
M-phase (Mitotic phase)
series of events wherein each cell divides to form to new daughter cells which are exactly identical to the mother cell
Mitosis
division of the nucleus, with its contents (duplicated chromosomes: 2n), into two identical nuclei
▪ occurs in body or somatic cell
mitosis
What events take place in Prophase (mitosis)? (5)
-Chromatin in the nucleus begins to condense, become visible in microscope
-Chromosomes are thickened and become shortened
-Centrioles begin moving to the opposite ends of the cell
-Fibers extend from the centromeres
-Nucleoli and nuclear membrane completely disappear
What events take place in Metaphase (mitosis)?
(4)
-chromosomes move along the middle of the cell
-Centrioles reached the opposite end
-Chromosomes become attached to the spindle fibers, move toward equator
-Chromosomes tightly coiled and discrete, very condensed
What events take place in Anaphase (mitosis)?
(2)
-Early anaphase: centromeres are duplicated and start moving apart; sister chromatids start separating
-Late anaphase: two identical sets of chromosomes move toward the opposite poles, spindle begine to disappear
What events take place in Telophase (mitosis)?(4)
-Chromatids arrive at the opposite poles
-enclosed in a nuclear membrane from their respective poles
-Chromosomes begin to thin out, uncoil, and no longer visible
-Spindle fibers disperse and cytokinesis may also begin
this division of cytoplasm usually follows mitosis.
cytokinesis
In plant tissues – the cytoplasm is divided via ____ where separation starts from the inside of the cell towards the periphery (in-out).
cell plate formation
In animal tissues - cell cytokinesis occurs via ___ starting from the periphery(out-in).
furrowing or cleavage formation
a.k.a resting phase; not actively preparing to divide
G0 phase
process by which gametes are generated for reproduction
Meiosis
occurs during gametogenesis; chromosome number turns to half (n)
Meiosis
this meiosis involves the separation of homologous chromosomes resulting in two cells with haploid (n) chromosome number
Meiosis I or reductional division
this meiosis happens when the two haploid cells proceed to the second division involving only the separation of chromatids producing four haploid cells
Meiosis II or equational division
begins after the G2 phase
Meiosis I
Substages of phrophase 1: (5)
Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
This substage in Phrophase 1 is where synapsis occur, forming bivalents
zygotene
This substage in Phrophase 1 is where crossing over happens
Pachytene
What happens in Metaphase 1? (2)
-bivalents align at the metaphase/equatorial plane
-Centromeres attached to the spindle fibers
What happens in Anaphase 1? (1)
Univalents in each bivalent separate from each other
What happens in Telophase 1? (1)
-Chromosomes regroup and their coiled structures begin to relax
In some species, no cytokinesis happens after Meiosis I. a
brief transitional stage called ___ occurs before the cell proceeds to the next stage.
interkinesis
meiosis II starts with __ cells
haploid
what is the product at the end of meiosis II?
formation of four (4) haploid daughter cells, each having only one chromosome of each homologous pair
The sequential events of the cell are directed by a distinct ___ which is similar to a clock; like a check-point
cell cycle control system,
Two types of regulatory proteins are involved in cell cycle control:
cyclins
cyclin-dependent kinases (Cdks)
each somatic cell nucleus has the same chromosomes—and therefore the same set of genes—as all other somatic cell nuclei. This is known as ____
genomic equivalence.
what factors could elad to differential gene expression? (3)
-regulatory mechanisms targeting DNA access, -RNA production and processing,
- protein synthesis and modification
is 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
is a process by which cells become specialized and take on specific roles in an organism.
Differential Gene Expression
gene expression can be regulated at four levels
Level 1: Differential gene transcription
Level 2: Selective pre-messenger RNA processing
Level 3: Selective messenger RNA translation
Level 4: Differential posttranslational protein modification
regulates which of the nuclear genes are transcribed into pre-messenger RNA.
Level 1: Differential gene transcription
regulates which parts of the transcribed RNAs are able to enter the cytoplasm and become messenger RNAs.
Level 2: Selective pre-messenger RNA processing
regulates which of the mRNAs in the cytoplasm are translated into proteins.
Level 3: Selective messenger RNA translation
regulates which proteins are allowed to remain and/or function in the cell.
Level 4: Differential posttranslational protein modification
sequence of events that enables the use and transfer of information to make the proteins of a cell
Central Dogma
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 ___.
heterogeneous nuclear ribonucleic acids (hnRNA); pre-mRNA
process of copying DNA into RNA;
Transcription
RNA produced from a given gene is often referred to as a __
transcript
the pre-mRNA strand will undergo processing to excise the noncoding domains and protect the ends of the strand to yield a ___ molecule
messenger RNA (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; it also unveils the complementary sequence of DNA three bases at a time
messenger RNA (mRNA)
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
