Bio 3 exam

DNA polymerase

The enzyme that synthesizes new DNA strands by adding nucleotides to a growing strand during replication.

Semi conservative

A model of DNA replication where each new DNA molecule contains one original (parental) strand and one new synthesized strand.

origins of replication

Specific DNA sequences where replication is initiated, allowing the DNA to begin unwinding.

Replication fork

A Y-shaped region where the DNA double helix is unwound and new strands are synthesized.

Replication bubble

A region where DNA has opened at the origin, forming two replication forks moving in opposite directions.

Leading strand

The DNA strand that is synthesized continuously in the same direction as the replication fork.

Lagging strand

The DNA strand that is synthesized discontinuously in short segments opposite fork’s movement.

Helicase

An enzyme that unwinds and seperates the DNA strands by breaking hydrogen bonds

Primer

A short RNA sequence that provides a starting point for DNA synthesis

Primase

An enzyme that synthesizes RNA primers needed to initiate DNA replication

Okazaki fragments

Short DNA segments formed on the lagging strand that are later joined together

Ligase

An enzyme that joins DNA fragments by forming covalent bonds between them

Proofreading

The ability of DNA polymeraseto detect and correct errors during replication

Nucleotide excision repair

A repair mechanism that removes damaged DNA segments and replaces them with correct nucleotides

Point mutation

A mutation involving a change in a single nucleotide base

Missense mutation

A mutation results in a different amino acid being incorperated into a protein

Nonsense mutation

A mutation that introduces a premature stop codon, leading to a shortened protein

Silent mutation

A mutation that does not change the amino acid, due to redundancy in the gentic code

Insertion

The addition of one or more nucleotides into a DNA sequence

Deletion

The removal of one or more nucleotides from a DNA sequence

Frameshift

A mutation caused by insertion or deletion that alters the reading frame of the gene

Duplication

A mutation where a segment of DNA is copied and repeated

Translocation

A mutation where a segment of DNA is moved to a different chromosome or location

Germline mutation

A mutation that occurs in reproductive cells and can be inherited by offspring

Somatic mutation

A mutation that occurs in body cells nd is not passed to offspring

Cell cycle

The ordered series of events in which a cell grows, replicates its DNA and divides into two daughter cells

Mitosis

The process of nuclear division where duplicated chromsomes are evenly seperated into two identical nuclei

DNA synthesis (replication)

The process by which a cell copies its DNA to prepare for cell division

Chromatin

DNA is in a loosely packed form when the cell is not dividing

Chromosome

DNA in a condensed, organized form during cell division

Gap 1 (G1)

The phase where the cell grows and preforms normal functions

Synthesis (S)

DNA is replicated (copies)

Mitosis (M)

Cell divides into two cells

Interphase

The stage of the cell cycle where the cell grows, performs normal functions, and replicates it DNA in preperation for division.

Prophase

Chromatin condenses into visible chromosomes and the mitotic spindle begins to form.

Prometaphase

The nuclear envelope breaks down, and the spindle fibers attach to chromosomes and kinetochores.

Metaphase

Chromosomes align at the metaphase plate, ensuring each daughter cell will receive identical chromosomes.

Anaphase

Sister chromatids seperate and are pulled to opposite poles of the cell

Telephase

Two nuclear envolopes form and chromsomes begin to decondense back into chromatin

Cytokinesis

The division of the cytoplasm, resulting in two gentically identical daughter cells

Spindle

A structure made of microtubules that seperate chromsomes during cell division

Centrosome

The main microtubule- organizing center that helps form the spindle

Checkpoint

A regular point where the cell verifies DNA integrity and proper conditions before proceeding in the cell

Growth factor

A signaling molecule that stimulates cell growth, division or survival

Cancer

A condition characterized by uncontrolled cell division due to loss or normal cell cycle regulation

Metastasis

The process by which cancer cells spread from the original site to other parts in the body

Apoptosis

A regulated process of programmed cell death that removes damaged or unnecessary cells

Oncogene

A gene that promotes cell division and can lead to cancer when mutated or over expressed

Tumor supressor

A gene that inhibits cell division or promotes repair/ apoptosis; loss of function can lead to cancer.

DNA

A double strand molecule that stores and trasmits hereditary genetic information in cells.

RNA

A usually single stranded nucleic acid involved in gene expression, espicially in carrying instructions from DNA to make proteins.

Nucleotide

The basic unit of nucleic acids, consisting of sugar, phosphate group and nitrogenous base.

Sugar

A five-carbon molecule in nucleotides (ribose or deoxyribose) that forms part of the backbone of DNA and RNA.

Phosphate

A negatively charged group that links sugars together to form the sugar phosphate backbone of nucleic acids.

Base

A nitrogen-containing molecule (A, T, G, C or U) that pairs specifically to encode gentic information

Ribose

A five carbon sugar found in RNA, characterized by having a hydroxyl (-OH) group at the 2’ carbon

Deoxyribose

A five carbon sugar found in DNA, lacking on the oxygen atom at the 2’ carbon.

Adenine

A purine base that pairs with thymine in DNA and Uracil in RNA

Thymine

A pyrimidine base found in DNA that pairs with Adenine

Guanine

A purine base that pairs with cytosine in both DNA and RNA

Cytosine

A pyrimidine base that pairs with guanine in both DNA and RNA

Uracil

A pyrimidine base found in RNA that pairs with adenine instead of thymine

Strand

A linear chain of nucleotides linked by phosphodiester bonds

Backbone

The repeating sugar phosphate structure that supports a nucleic acid strand

Genes

Segments of DNA that contain instructions to produce function RNA or proteins

Genetics

The study of genes, genetic variation and inheritance in organisms

Inheritance

The transmission of genetic information from one generation to the next

Hereditary information

Genetic instructions encoded in DNA that determine traits and are passed too offspring

5’ end

The end of a nucleic acid strand with a free phosphate group attached to the 5’ carbon of the sugar

3’ end

The end of the nucleic acid strand with a free hydroxyl (-OH) group on the 3’ carbon of the sugar.

Base pairing

The specific hydrogen bonding between complementary bases (A-T or A-U, and G-C).

Complementary

Refers to sequences that can form base pairs with each other according to base pairing rules.

Antiparallel

The orientation of two DNA strands running in opposite directions (one 5’-> 3’, the other 3’-> 5’).

Double helix

The twisted, ladder-like structure formed by two antiparallel DNA strands.

Replication

The process by which DNA is copied to produce two identical DNA molecules before cell division.

Template strand

The DNA strand used by RNA polymerase to synthesize a complementary RNA sequence.

Non template strand

The DNA strand not used during transcription, whose sequence matched the RNA (except T-> U).

Transcription

The process of synthesizing RNA from a DNA template.

RNA polymerase

An enzyme that builds RNA by adding complementary RNA nucleotides during transcription.

Transcript factors

Proteins that regulate gene expression by helping RNA polymerase bind to DNA and initiate transcription.

Promoter

A specific DNA sequence where RNA polymerase and transcription factor bind to begin transcription.

RNA transcript

The RNA molecule produced during transcription is complementary to the template DNA strand.