Vocab BSC1105

Sister chromatids

identical copies of a chromosome; formed in the S phase of the cell cycle. Separate during cell division

Centromere

the region of the chromosome that hold the two sisiter chromatids together during mitosis (cell division)

Cell cycle

series of events in which a cell grows and divides in order to form two daughter cells

Interphase

when the cell undergoes normal processes while also preparing for cell division. It consists of G1, S, and G2 phases

Mitosis

is the division of the nucelus. It's series of phases are prophase, metaphase, anaphase, and telophase (PMAT)

Prophase

first and longest phase of mitosis. During it the nucelar envelope breaks down, chromosomes visible, spindle fibers begin to form.

Metaphase

second phase of mitosis. During metaphase the chromosomes line up across the center of the cell (metaphase plate). The chromosomes line up in a single file line along the equator (the metaphase plate) of the cell. This ensures that when they pull apart, each new cell gets exactly one copy of every chromosome.

Anaphase

the third phase of mitosis. During __, the chromosome seperates and move toward opposite poles. The spindle fibers pull the sister chromatids apart. They move to opposite poles of the cell. Once they are separated, they are considered individual chromosomes.

Telophase

the final stage of mitosis. During it, chromosomes move to opposite poles and decondense. The chromosomes reach the ends of the cell and begin to uncoil back into chromatin. Two new nuclear envelopes form around the DNA at each end. The spindle fibers disappear.

Mitotic spindle

a structure of microtubule that orchestrates the movement of chromosomes during mitosis and meiosis.

Cleavage furrow

the actin ring constriction in animal cell-cytokinesis that is responsible for dividing the cytoplasm.

Cell plate

a structure formed during plant cell-cytokinesis when Golgi vesicles fuse at the metaphase plate. It later forms a cell wall that divides the two daughter cells.

Cell cycle check points

are critical internal control mechanisms that determine whether a cell is prepared to move on to the next stage of division. At each checkpoint, the cell cycle is stopped until specific conditions are met, ensuring that the resulting daughter cells are healthy and genetically identical to the parent. There are three major checkpoints: G1 checkpoint, G2 checkpoint and M checkpoint

Cancer

cancer encompasses various diseases resulting from the shared mechanism of uncontrolled cell division.

Homologous chromosomes

chromosomes of the same length with genes in the same location; diploid organisms have pairs of homologous chromosomes.

Diploid

refers to cells, nucleus, or organisms with two sets of chromosomes (2n)

Haploid

describes a cell, nucleus, or organism that contains one set of chromosomes (n)

Gametes

a haploid reproductive cell or sex cell. Either a sperm or egg

Fertilization

the union of two haploid cells from two individual organisms

Meiosis

a nuclear division process that results in four haploid cells. Meiosis I is the separation of homologous chromosomes and Meiosis II is the separation of sister chromatids.

Karyotype

is the number and appearance of an individual's chromosomes, including their size, banding patterns, and centromere position.

Nondisjunction

incomplete separation and migration of synapsed homologous chromosomes to separate poles during the first cell division of meiosis.

Genetics

the scientific study of heredity

True-breeding

a term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate.

Hybrid

offspring of crosses between parents with different traits

P generation

the first generation in a cross

F1 Generation

the first filial generation in a cross; the offspring of the parental generation

F2 Generation

the second filial generation. They're produced when F1 individuals are self-crossed or fertilized with each other

Alleles

a variant form of a specific gene, representing different DNA sequences at a given genomic location

Homozygous

an individual having two identical alleles (versions) of a specific gene, one inherited from each parent. These matching alleles can be both dominant (AA) or both recessive (aa).

Heterozygous

having two different alleles (versions) of a specific gene, one inherited from each parent. It is key genetics term describing genotype (such as Aa) where the paired alleles differ, resulting in traits determined by dominance, recessiveness, or co-dominance

Dominant

a genetic variant that masks the effect of a recessive allele in an individual's phenotype. Requires only one parent to pass it on

Recessive

refers to a phenotype or allele that is only expressed when an organism inherits two identical copies of that gene (aa) - one from each parent. It is masked by a dominant allele when the genotype is heterozygous (Aa)

Genotype

the specific genetic makeup or combination of alleles (AA, Aa, aa) inherited by an organism for a particular trait or set of traits. It represents the internal genetic code, distinct from the phenotype (physical expression), and influences how an organism develops and functions, sometimes interacting with the environment.

Phenotype

the observable physical or biochemical characteristic of an organism, determined by both its genetic makeup (genotype) and environmental influences. Includes traits like height, hair color, blood type, and behavior.

Monohybrid cross

a genetic mating experiment between two organisms that are each hybrid (heterozygous) for a single, specific trait. It focuses on tracking how alleles for one trait are passed from parents to offspring, typically resulting in a phenotypic ratio in the generation.

Dihybrid cross

a breeding experiment between two organisms that are identical hybrids (heterozygous) for two specific traits. It studies how two different genes—located on separate chromosomes—assort independently, resulting in a predicted 9:3:3:1 phenotypic ratio in the offspring, based on Mendel's law of independent assortment

Incomplete dominance

a form of non-Mendelian inheritance where neither allele is completely dominant over the other, resulting in a heterozygous phenotype that is an intermediate blend of the two homozygous phenotypes. Rather than one trait masking the other, they produce a "mixed" trait (e.g., red and white parents producing pink offspring)

Codominant

a genetic inheritance pattern where two different alleles (versions of a gene) are equally expressed in a heterozygous individual, resulting in a phenotype that shows both traits simultaneously

Multiple alleles

the existence of three or more alternative forms (alleles) of a specific gene within a population, rather than just the two typical of Mendelian genetics.

Sex-linked genes

genes located on the sex chromosomes (X or Y) that determine traits unrelated to female or male reproductive anatomy.

Sex chromosomes

a specialized pair of chromosomes that determine an organism's biological sex, distinct from autosomes. In mammals, these are typically X and Y chromosomes (XX for female, XY for male),

X-linked genes

genes located on the X chromosome, one of the two sex chromosomes in humans and many animals. Because males (XY) have only one X chromosome and females (XX) have two, X-linked traits—especially recessive ones—often manifest differently by sex, with males more frequently affected because they lack a second X to mask the mutation

Nucleotide

A building block of DNA consisting of a five-carbon sugar covalent bonded to a nitrogenous base and a phosphate group.

Deoxyribonucleic acid

known as DNA

Sugar-phosphate backbone

The alternating chain of sugar and phosphate to which the DNA and RNA nitrogenous bases are attached.

Helicase

Untwists the double helix of DNA at the replication forks.

Double helix

Are two strands of nucleotides wrapped around each other in a spiral shape; structure of DNA.

Semiconservative model

Are double-stranded DNA that contains one parental and one daughter strand during replication.

DNA polymerase

a type of enzyme, often abbreviated as DNAP or Pol, crucial for life, that synthesizes new DNA molecules by assembling nucleotides on a template strand

DNA ligase

Catalyzes DNA fragments joining together. essential enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond between adjacent 3-hydroxyl and 5-phosphate ends. It acts as a molecular "glue," sealing nicks in the DNA backbone during replication, repair, and recombination.

Okazaki fragment

short, discontinuous segments of DNA synthesized on the lagging strand during DNA replication. Because DNA polymerase only works in one direction, the lagging strand is built in small, backward-moving segments that are later linked together by DNA ligase to form a continuous chai

Transcription

the foundational biological process where a specific segment of DNA is copied into a new, single-stranded RNA molecule (mRNA) by the enzyme RNA polymerase. It is the first step of gene expression, converting genetic instructions into a portable format used to synthesize proteins in the cytoplasm

Translation

the process where ribosomes in the cytoplasm decode messenger RNA (mRNA) to synthesize specific polypeptide chains, forming proteins. It translates the genetic language of nucleic acids (nucleotide sequences) into the language of proteins (amino acid sequences), functioning as the second major step in gene expression

Codon

a sequence of three consecutive DNA or RNA nucleotides (a trinucleotide) that functions as a unit of genomic information, coding for a specific amino acid or signaling the start/stop of protein synthesis. During translation, these triplets guide the assembly of amino acids into proteins

RNA polymerase

Merge an RNA strand from a DNA template strand. a multi-subunit enzyme that catalyzes transcription, the process of synthesizing RNA from a DNA template.

Messenger RNA

a single-stranded molecule that carries genetic instructions from DNA in the nucleus to the cytoplasm, acting as a blueprint for building proteins. Created during transcription, it tells ribosomes which amino acids to link to form specific proteins, essential for cell function. It is critical for gene expression and is used in vaccines to teach cells to produce antigens

Introns

a non-coding nucleotide sequence within a gene that is transcribed into pre-mRNA but removed (spliced out) during RNA maturation. Found primarily in eukaryotes, these intervening sequences do not code for proteins but are essential for regulation, splicing, and increasing proteome diversity

Exons

a segment of DNA or RNA molecule containing information that codes for a protein or peptide sequence. During RNA splicing, __ are retained in the mature mRNA molecule after introns (non-coding regions) are removed. are covalently bonded together to form the functional mRNA that is eventually translated into proteins

RNA processing

the post-transcriptional modification of primary RNA transcripts (pre-mRNA) into mature, functional RNA molecules (mRNA, tRNA, or rRNA). Occurring primarily in the eukaryotic nucleus, it involves capping, splicing, and polyadenylation to ensure stability, proper export, and accurate translation into proteins

Transfer RNA

a small RNA molecule that acts as an adaptor during protein synthesis, linking messenger RNA (mRNA) codons with specific amino acids. __ translates genetic code by carrying amino acids to the ribosome, matching its anticodon to the complementary mRNA codon to assemble proteins

Anticodon

a trinucleotide sequence located at one end of a transfer RNA (tRNA) molecule, which is complementary to a corresponding codon in a messenger RNA (mRNA) sequence

Ribosomal RNA

a type of non-coding RNA that serves as the primary structural and functional component of ribosomes, the cellular machines responsible for protein synthesis. It makes up roughly 80-90% of total cellular RNA, providing the scaffold for ribosomes and catalyzing the formation of peptide bonds to assemble proteins

Mutation

a permanent alteration in the DNA sequence of an organism, acting as a change in the "text" of the genetic code. These changes can occur due to DNA replication errors during cell division or environmental factors like UV radiation. Mutations can be neutral, beneficial, or harmful to an organism