Unit 1: Chromosomal Structure Flashcards
A non-sex chromosome
Autosomal chromosome
A particular chromosomes That are involved in determining the sex of an organism. The paired sex chromosomes do not carry an identical complement of genetic information. The X chromosome, being larger, carries many more genes when does the Y
Sex chromosome
An organism with two copies of each chromosome
Diploid (46 chromosomes) 
A term used when a cell has half the usual number of chromosomes.
Haploid
Ex: Gameats (Sperm and ova)
Deoxyribonucleic acid polymer: The molecule that carries genetic information
DNA
The physical characteristics of an individual
Phenotype
A phenotype or allele that completely masks the presence of the other, recessive allele in the heterozygote
Dominant
A phenotype or allele exhibited only when homozygous
Recessive
The fundamental unit of heredity; A specific section of DNA within a chromosome
Gene 
The genetic makeup of an individual; The allele(s) possessed at a given locus
Genotype
An individual with two different alleles of a given gene or locus
Heterozygote
An individual with two identical alleles of a given gene or locus
Homozygote
A specific location on a chromosome
Locus
Genomic DNA organized into a number of rod–shaped organelles
Chromosomes
The number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual.
Karyotype
Packed chromosomes in cell complex with several classes of specific proteins
Chromatin
Each complex of DNA with core histones
Nucleosome
A small but important subset of genes encoded in the human genome resides in the cytoplasm in the mitochondria. The mitochondrial DNA molecules is only 16 kb, Encodes only 37 genes. 
Mitochondrial chromosome
Alternative forms of a gene
Alleles
A pair of chromosomes carrying matching genetic information, typically have the same genes in the same order.
Homologous chromosomes
Ex: Moms chromosome number one and dad’s chromosome number one. 
The two identical chromosomes that result from DNA replication.
Sister chromatids
A region of the chromosome where sister chromatids are held together by proteins
Centromere
Natural end of a eukaryotic chromosome composed of a usually repetitive DNA sequence and serving to stabilize the chromosome
Telomere
Chromosomes are only found in ___________ cell Nucleus
Eukaryotic
Chromosomes can be seen in condensed form only during ____________. 
Nuclear division
During interphase genetic material occupies areas of nuclei in the form of _________. 
Chromatin
Chromatin functions to….
package and compressed DNA, exposing specific genes for transcription during certain phase of cell lifespan and condenses the rest
Individual chromosome can’t be distinguished except ______________ probes complementary to specific chromosomal sequence. 
Fluorescent
Which arm of the chromosome is short? And which one is long? 
P- short arm
q- Long arm
What is the best phase of mitotic cell division to view a chromosome?
Metaphase
In what mitotic cell division phase is DNA becoming more condense?
Prophase 
Each homologous set is made up of ____ Homologues
2
- One from each parent
- not the same as sister chromatid
23rd chromosome is the…
Sex chromosomes
Chromosomes are most condensed (Thickened)  And highly coiled in what phase? 
Metaphase
- Most suitable for visual analysis
The analysis of ___________ chromosomes is one of the main tools of classical cytogenetics and cancer studies. 
Metaphase
______________ chromosomes make the classical picture of chromosomes (Karyotype). 
Metaphase
DNA double helix of about 2.0 nm thick is wrapped around a core of four pairs of histone molecules to form….
Nucleosomes 
What forms the core of Nucleosome?
Four pairs of histones
_________ DNA connects between Nucleosomes.
Linker ?
Nucleosomes attached together by peripheral histone and condense forming a fiber of about _____nm thick.
30
The nucleosome of fibers form loops radiating from scaffolding non-histone Proteins to form the DNA proteins complex of chromatin _________ During cell division.
Fibers
As a result of DNA replication, each chromosome becomes two ______________ attaching at centromere of about 1400 nm in thickness in metaphase.
Sister chromatids
Kinetochore
?
____________ makes out chromosomes.
Chromatin
- Changes to chromatin structure can prevent or allow certain regions of the genetic code to be read and expressed
Is the genetically active type of chromatin involved in transcribing RNA to produce proteins
Euchromatin
What is the perdominant type of chromatin found in cells during interphase?
Euchromatin (more diffused) 
Is genetically inactive type of chromatin
Heterochromatin (more concentrated along chromosomes at certain regions of the structures, such as centromeres and telomeres)
Does heterochromatin or euchromatin stain darker? 
Heterochromatin (more condensed) 
- Silenced genes (Methylated)
- Gene poor (high AT content)
Heterochromatin
- Gene expressing
- Gene rich (Higher GC content) 
Euchromatin
Sister chromatids are joined together by a common __________.
Centromere
Site of crossing over
Chiasmata
- leads to diversity
Pairing of two homologous chromosomes that occur during meiosis
Synapsis 
Synapsis occurs during _________
Prophase 1
When the homologs line up besides each other and form a zipper-like connection between each other
Synapsing
(The zipper like connection is chiasmata) 
Chromosomes regions (bands) are named numerically starting from the….
Centromere
What is the nomenclature of chromosomes? 
- Chromosome number written first
- Location on the short or long arm
- Region of the arm (specific band) 
What are the different mutation types?
- t (translocation)
- del (Deletion)
- ins (dup) (insertion)
- inv (Inversion)
