2.1 - Chromosome Discovery and Chromosome Structure Flashcards
Who is the father of Genetics?
Gregor Mendel
These are carried traits from one generation to the next
Medelian “factors”
He recognized and explored the fibrous network within the nucleus which is termed now as chromatin or “stainable material”
Walther Flemming
- He observed cells in various stages of division
- He recognized that chromosomal movement during mitosis offered a mechanism for the precise distribution of nuclear material during cell division
Walther Flemming
He provided the first evidence that germ cell chromosomes imparted continuity between generations
Studied cytoplasmic changes to form new offspring from union of gametes
Theodor Boveri
His work on Ascaris embryos provided one of the first descriptions of meiosis
Theodor Boveri
He is one of the pioneers of embryology
Theodor Boveri
He confirmed and expanded upon Boveri’s observations
Walter Sutton
He described the configurations of individual chromosomes in cells at various stages of meiosis (testes of Brachystola magna or grasshopper)
Walter Sutton
Flemming - studied mitosis; Sutton & Boveri studied ________
meiosis
The division in meiosis can be described at both the ____ level and ____ level
nuclear level ; chromosomal level
Out of the 4 products of meiosis in females, only ____ of them becomes a mature egg (ovum), while the ____ becomes polar bodies
1 ovum ; 3 polar bodies
He investigated the mechanisms of heredity and developed the Chromosomal theory of inheritance and the Idea of chromosomal individuality
Theodor Boveri
Boveri hoped that his experiments would also help to distinguish the roles of the nucleus and the cytoplasm in ___________
embryogenesis
It is the influence that certain cytoplasmic contents have on the behavior of the nucleic material and the differentiation of the cell.
Cytoplasmic specification
True or False
Boveri was also able to demonstrate that each chromosome carried specific hereditary information, and that the chromosomes were not interchangeable—they summed to the total hereditary structure
True
In 1910, ge experimentally demonstrated Chromosomal Theory of Inheritance using Drosophila melanogaster
Thomas Hunt Morgan
What insect did Morgan used for his “Fly Room” experiments?
Drosophila melanogaster or Fruit fly
In 1916, he helped establish the chromosomal basis of heredity and sex through nondusjunction
student of Morgan
Calvin Bridges
It is the procsses that causes chromosomes, under some circumstances, to fail to separate when forming sperm and egg cells
Nondisjunction
It caused sperm or egg cells to contain abnormal amounts of chromosomes
These are threadlike structures or “colored bodies” (chroma = color ; soma = body)
Factors that distinguish one species from another
chromosome
What are the components of a chromosome?
- protein
- single molecule of DNA (runs several thousands of kilobases)
- some minute RNA
In what experiemt did scientists prove that it is in fact DNA and not protein that is being passed from gen to another?
rough and smooth strain bacteria
The number of stained regions
What factors of a chromsome distinguishes one specie to another?
- number
- sets of genes
It is a type of protein found in chromosomes and binds to DNA and give chromosomes their shape, and help control the activity of genes
Histone proteins
What type of protein wraps and pulls around the chromosome?
- it is involved in the wrapping of DNAs until it becomes a hyperlooped structure and creates the chromosome
Histone proteins
True or False
All chromosomes have a constriction/region of centromere
False
In ________, chromosomes ensure daughter cell retains its own complete genetic complement
Mitosis
In ________, chromosomes enable each mature ovum and sperm to contain a unique single set of parental genes
stage where diploid (2n) becomes haploid
Meiosis I
What comprises of the human chromosome?
- 44 autosomes
- 2 sex chromosomes
Among the phases under mitosis, which phase contains the chromosomes that are thick, easily stained, and used in karyotyping?
Metaphase chromosomes
Replicated condensed chromosome with sister chromatids
In aligning the chromosomes in karyotyping, what should be the order of the chromosomes?
Biggest to smallest (according to size)
In the sex chromosomes (X & Y), which is smaller in size?
Y sex chromosome
Where do you find the Extra-chromosomal DNA in animals?
Mitochondria
What is the pattern of inheritance of mitochondrial DNA?
Matrilineal (only get it from the mothers)
Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes (MELAS) syndrome is an example of what disease
Mitochondrial disease
It is the region of metaphase chromosomes that tie together sister chromatids
centromere
It is a region in the end of linear chromosomes or eukaryotic chromosomes (non-existent in circular chromosomes/prokaryotic)
telomere
“aglets”
- It protects the chromosomes from being destroyed at the tips
- play an imp. role in attaching cells during meiosis, spec. in sex cells (attachment of cells to the side nuclei which allows for the pairings of homologous chromosomes)
- maintains the information code of the DNA
telomere
It is the ribonucleoprotein enzyme responsible for maintenance of the length of telomeres by addition of guanine-rich repetitive sequences
Telomerase
What are the stages of the looping of the DNA until it reaches the highly-coiled struct.?
- DNA Double helix
- Wrapping og DNA around a histone octamer with histone H1 (closer of the loop)
- Formation of a 3D zigzag structure via histone H1 and other DNA-binding proteins – It becomes a nucelosome (“beads on a string”)
- anchoring of radial loops in the nuclear matrix —- radial loop domains
- further contraction of radial loops
- foprmation of a scafold from the nuclear maix and further complication of all radial loops
- Result: metaphase chromosome
Histone proteins is rich in ____, which allows for positive chargers to present and attract the negatively charged DNA around the phosphate region
basic amino acids
In the bead on a string is composed of _ subunits of globular proteins plus 1 H1 protein found at the ____ of the bead
8 ; periphery
A nucelosome “bead” is composed of what
8 histone molecules wrapped around by 147 nucleotide pairs of DNA
Besides the histone proteins, the chromosome also has helper proteins called _______
anchoring proteins
These are two identical strands which are the result of DNA replication
chromatids
- Central region
- Primary constriction where sister chromatids are linked
- Consists of several hundred kilobases of repetitive DNA
- Responsible for chromosome movement at cell division
centromere
It is a region in the centromere that serves as an attaching point for microtubules and facilitates spidle formation
kinetochore (part of MTOC)
It is the whole region in the centromere including the kinetochore where microtubules emerge
Microtubule organizing center (MTOC)
The centromere divided the chromosome into:
short arm: p (petite)
long arm: q (queues or “g” = grande)
True or False
Not all chromosome is nicely divided into p and q arms
true
Molecularly, we can count the number of ____ to identify which is the p and q arms
bases
There are ____ chromosomes that have prominent long and short arms
13
Chromosome Types based on number of centromeres
- the only normal kind of chromosome (accdg. kay ian haha, since ito lang yung napapass)
- Single centromere
- Reliably transmitted from parental to daughter cells
Monocentric
Chromosome Types based on number of centromeres
- Lacks centromere
- genetically unstable because they cannot be maneuvered properly during cell division and are usually lost (because there is no centromere = no attachment site for microtubules to pull the chromosome w dynein and kinesin towards the pole)
Acentric
Chromosome Types based on number of centromeres
- two centromeres
- also genetically unstable because it is not transmitted in a predictable fashion
Dicentric
Chromosome types are categorized based on what factors?
- numbers of centromeres
- centromere position
- arms ratio
Chromosome Types based on centromere position
- Middle = yielding arms of roughly equal length
- Centromere is centrally located
- 5 pairs in humans
Metacentric
The shape of the metacentric chromosome is ________ shape
X shape
1st, 3rd, 16th, 19th and 20th are examples what type of chromosome (based on centromere position)
metacentric
Chromosome Types based on centromere position
- Off-center centromere; “q” arm is longer
- Unequal length of chromosome arms
- 13 pairs
Submetacentric
Chromosome Types based on centromere position
2, 4 - 12, 17, 18, X are examples of what type of chromosome (based on centromere position)
Submetacentric
- Acro = peak
- centromere severely off-set from centre
- Very close to one end; yielding a small short arm
- Often associated with small pieces of DNA called satellites, encoding rRNA
- 5 pairs in humans
Acrocentric
In acrocentric type of chromosome, the p region is called a ________ region (since it is too short) which contain genetic information
satellite
13 - 15, 21, 22, Y are examples of what type of chromosome (based on centromere position)
Acrocentric
This is a type of centromere found at end of chromosome = meaning no p arm exists
chromosome not found in humans
telocentric
What are the shapes of the following chromosome types:
- metacentric
- submetacentric
- acrocentric
- metacentric = V-shaped
- submetacentric = J-shaped
- acrocentric = i-shaped
It determines the ratio of p and q arms for each chromosome type (L/s)
proposed by Levan et al. (1964)
Arms ratio (r)
Telomere is a tandem repeats of the hexameric sequence ________
‘TTAGGG’
What formation allows the elongation of the telomere and maintains telomere region
lariat formation
It prevents abnormal end-to-end fusion of chromosomes
telomere
During early meiosis, telomeres play the distinctive function of ________ chromosomes to the inner nuclear membrane
anchoring
as a consequence of the nuclear membrane polarization, telomeres cluster together into a ________ , which facilitates pairing and recombination of the homologous chromosomes
bouquet configuration
This hypothesis proposes that the ends of linear DNA cannot be replicated completely during lagging strand DNA synthesis.
End of Replication Problem Hypothesis
Telomerase replenishes the ________ and requires no ATP
telomere cap
In most multicellular eukaryotic organisms, telomerase is active only in:
- germ cells
- some stem cells
- certain WBC
Telomerase can be reactivated and telomeres reset back to an embryonic state by _______
somatic cell nuclear transfer
The phenomenon of limited cellular division was first observed by ________ , and is now referred to as the Hayflick limit
Leonard Hayflick
