Exam 3 | BSC2010 Vocabulary Flashcards

Double Helix

The spiral structure of DNA

Histones

Proteins that package and order DNA into structural units called nucleosomes, playing a crucial role in gene regulation.

Nucleosomes

Structural units of DNA formed by histones that help organize and compact DNA into chromatin.

Chromatins

Complex structures of DNA and proteins that form chromosomes during cell division. Chromatin helps in regulating gene expression and DNA replication.

Chromosomes

(Compacted Chromatin) Thread-like structures made of DNA and proteins that carry genetic information, formed from chromatin during cell division. They are visible during mitosis and meiosis.

Genome

The complete set of genetic material in an organism.

Genes

A specific section of DNA with some kind of trait, found in different locations throughout specific chromosomes.

Nucleotides (monomer of Nucleic Acids)

Sugar, Phosphate Group, Nitrogenous Base

Telomere

shorten each time a cell divides, which can lead to aging or cell death when they get too short.

Sister Chromatids

Sister chromatids are two identical copies of a chromosome

Centromere

region where sister chromatids join

Interphase

Largest part of cell cycle, consists of G1, S, and G2

Gap 1

cell goes through routine activities, growing and developing

Synthesis (S phase)

Results in 92 sister chromatids, or 46 duplicated chromosomes, replication happens here.

Gap 2

Cell continues to do routine activities and prepare for division.

Prophase

In prophase, chromatin condenses into visible chromosomes, each consisting of two sister chromatids. The nuclear membrane begins to break down, and the mitotic spindle starts to form, connecting to the centromeres of the chromosomes.

Metaphase

chromosomes line up along the cell's equator (metaphase plate) and attach to spindle fibers to ensure each new cell receives an identical set of DNA.

Anaphase

In anaphase, sister chromatids are pulled apart by the spindle fibers toward opposite ends of the cell, ensuring each new daughter cell will have its own complete set of chromosomes.

Telophase

During telophase, the separated chromosomes reach the opposite poles and begin to de-condense back into chromatin, while new nuclear envelopes form around each set to create two distinct nuclei.

Cytokinesis

While telophase finishes the nuclear division, cytokinesis is the physical act of the cell membrane pinching (in animal cells) or a cell plate forming (in plant cells) to split the cytoplasm into two independent daughter cells.

Benign

does not move (non-cancer)

Malignant

moves to other areas (metastasize)

indpendent assortment

During meiosis, pairs of homologous chromosomes line up and separate into gametes randomly and independently of other pairs, creating millions of possible genetic combinations.

random fertilization

The concept that any one unique sperm can fuse with any one unique egg, further increasing the genetic diversity of the resulting offspring.

non disjunction

An error in cell division where chromosomes fail to separate properly during meiosis or mitosis, resulting in daughter cells with an abnormal number of chromosomes (e.g., Down Syndrome/Trisomy 21).

aneuploidy

The condition of having an abnormal number of chromosomes in a cell (for example, having 45 or 47 chromosomes instead of the usual 46). It is typically caused by nondisjunction.

monosomic

A specific type of aneuploidy where a diploid cell is missing one chromosome from a homologous pair (designated as $2n - 1$).

trisomic

A specific type of aneuploidy where a diploid cell has one extra chromosome added to a homologous pair

polyploidy

A condition in which an organism has more than two complete sets of chromosomes (such as $3n$ or $4n$). This is very common in plants (like strawberries or wheat) but often fatal in animals.

deletion

A type of chromosomal mutation where a fragment of the chromosome is lost. This results in the missing of certain genes, which can lead to serious genetic disorders.

duplication

A mutation where a broken chromosome fragment attaches to its sister chromatid or a homologous chromosome, resulting in an extra copy of a specific DNA segment.

inversion

A chromosomal mutation where a segment of the chromosome breaks off, flips 180°, and reattaches in the reverse orientation.

translocation

A mutation where a fragment of one chromosome breaks off and attaches to a non-homologous chromosome (a different chromosome altogether).

down syndrome

A genetic disorder caused by Trisomy 21, where an individual has three copies of chromosome 21 instead of the usual two. This typically occurs due to nondisjunction during meiosis.

philadelphia chromosome

A specific genetic abnormality caused by a translocation between chromosomes 9 and 22. This exchange of genetic material creates an abnormally short chromosome 22, which is commonly associated with Chronic Myeloid Leukemia (CML).

DNA

A polymer of nucleotides; the genetic material.

Nitrogenous Bases

Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

Chargaff’s Rules

1. Base composition varies between species; 2. In any species, the number of A and T bases is equal, and the number of G and C bases is equal.

Double Helix

The form of native DNA, composed of two adjacent antiparallel polynucleotide strands.

Antiparallel

The arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite directions).

DNA Replication

The process by which a DNA molecule is copied.

Semiconservative Model

Type of DNA replication in which the replicated double helix consists of one old strand and one newly made strand.

Telomeres

Special repetitive, non-coding nucleotide sequences at the ends of eukaryotic chromosomal DNA molecules.

Telomerase

An enzyme that catalyzes the lengthening of telomeres in germ cells.

Nucleoid

A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated.

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes.

Histones

Proteins responsible for the first level of DNA packing in chromatin.

Nucleosome

The basic, bead-like unit of DNA packing in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone.

Histone Tail

The amino end of a histone protein that extends outward from the nucleosome.

Gene Expression

The process by which DNA directs protein synthesis; includes transcription and translation.

Transcription

The synthesis of RNA using a DNA template.

Messenger RNA (mRNA)

A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.

Translation

The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule.

Ribosomes

Complex particles that facilitate the orderly linking of amino acids into polypeptide chains.

RNA Processing

Modification of RNA primary transcripts, including splicing and the addition of 5' caps and poly-A tails (specific to eukaryotes).

Triplet Code

A genetic information system in which a set of three-nucleotide-long words specifies the amino acids for a polypeptide chain.

Template Strand

The DNA strand that provides the pattern for ordering the sequence of nucleotides in an RNA transcript.

Codons

mRNA nucleotide triplets, customarily written in the 5′ $\rightarrow$ 3′ direction.

Coding Strand

The non-template DNA strand, which has the same sequence as the mRNA (except with T instead of U).

Reading Frame

On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis.

Mutations

Changes in the genetic information of a cell.

Point Mutations

Changes in just one nucleotide pair of a gene.

Nucleotide-pair Substitution

The replacement of one nucleotide and its partner with another pair of nucleotides.

Silent Mutation

A nucleotide-pair substitution that has no observable effect on the phenotype (e.g., results in the same amino acid).

Missense Mutation

A nucleotide-pair substitution that results in a codon that codes for a different amino acid.

Nonsense Mutation

A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

Insertions

Additions of nucleotide pairs in a gene.

Deletions

Losses of nucleotide pairs in a gene.

Frameshift Mutation

A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.

Mutagens

Physical or chemical agents that interact with DNA and cause mutations.