chapter 4, genes and cell function Flashcards
What is Deoxyribonucleic Acid (DNA)?
The molecule that stores genetic information
DNA is essential for inheritance and biological information transfer.
What are the components of a nucleotide?
- Phosphate group
- Deoxyribose (sugar in DNA)
- Nitrogenous base (Adenine, Thymine, Cytosine, Guanine)
Nucleotides are the basic building blocks of nucleic acids.
What is the Double Helix?
The spiral shape of DNA, discovered by Watson & Crick
This structure is critical for DNA replication and function.
What is the Base Pairing Rule?
Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G)
This rule is fundamental for the complementary nature of DNA strands.
What is Chromatin?
Loosely coiled DNA and protein found in the nucleus
Chromatin is the form DNA takes when the cell is not dividing.
What is a Chromosome?
A tightly coiled structure of DNA seen during cell division
Chromosomes ensure DNA is accurately replicated and distributed.
What are Histones?
Proteins that help package DNA into chromatin
Histones play a crucial role in gene regulation.
What is a Genome?
The complete set of genetic material in an organism
The genome contains all the information necessary for the growth and functioning of an organism.
What is a Gene?
A segment of DNA that codes for a protein
Genes are fundamental units of heredity.
What is the Genetic Code?
The system that translates DNA sequences into proteins
The genetic code is universal among living organisms.
What is a Codon?
A three-nucleotide sequence in mRNA that codes for an amino acid
Codons are the basis for protein synthesis.
What is Ribonucleic Acid (RNA)?
A molecule that helps synthesize proteins
RNA plays a key role in translating genetic information into functional proteins.
What is Messenger RNA (mRNA)?
Copies genetic instructions from DNA and carries them to ribosomes
mRNA is crucial for the process of translation.
What is Transfer RNA (tRNA)?
Brings amino acids to the ribosome for protein assembly
tRNA ensures the correct amino acids are added to the growing polypeptide chain.
What is Ribosomal RNA (rRNA)?
A structural component of ribosomes
rRNA plays a vital role in the ribosome’s function during protein synthesis.
What is Transcription?
The process of copying DNA into mRNA
Transcription is the first step in gene expression.
What is Translation?
The process of converting mRNA into a protein
Translation occurs at the ribosome and is essential for protein synthesis.
What is RNA Polymerase?
The enzyme that creates mRNA from DNA
RNA Polymerase is crucial for the transcription process.
What is a Triplet Code?
A three-base sequence in DNA that corresponds to a codon
The triplet code is fundamental to the genetic code.
What is a Start Codon?
The first codon of an mRNA transcript (AUG, which codes for methionine)
The start codon signals the beginning of translation.
What is a Stop Codon?
A codon that signals the end of translation (UAA, UAG, UGA)
Stop codons do not code for an amino acid.
What is a Polyribosome?
A cluster of ribosomes translating the same mRNA
Polyribosomes allow for efficient protein synthesis.
What is DNA Replication?
The process of copying DNA before cell division
DNA replication is essential for genetic continuity.
What is Semi-Conservative Replication?
Each new DNA molecule contains one old and one new strand
This mechanism ensures accuracy in DNA replication.
What is DNA Helicase?
Unwinds the DNA double helix
DNA helicase is crucial for initiating DNA replication.
What is DNA Polymerase?
Enzyme that builds the new DNA strand
DNA Polymerase ensures the fidelity of DNA replication.
What is the Leading Strand?
The continuously synthesized DNA strand
The leading strand is synthesized in the same direction as the replication fork.
What is the Lagging Strand?
The DNA strand synthesized in short fragments (Okazaki fragments)
The lagging strand is synthesized in the opposite direction of the replication fork.
What is a Mutation?
A change in the DNA sequence
Mutations can lead to genetic diversity or diseases.
What is the Cell Cycle?
The life cycle of a cell, including growth and division
The cell cycle consists of several phases: G1, S, G2, and M.
What occurs during the G1 Phase?
Cell grows and carries out normal functions
G1 is the first phase of the cell cycle.
What occurs during the S Phase?
DNA replication occurs
The S phase is crucial for ensuring each daughter cell receives an identical set of DNA.
What occurs during the G2 Phase?
Cell prepares for mitosis
G2 involves the synthesis of proteins required for mitosis.
What occurs during the M Phase?
The cell divides (Mitosis)
M phase includes both mitosis and cytokinesis.
What is Mitosis?
Division of the nucleus into two identical daughter cells
Mitosis ensures genetic consistency across cells.
What happens during Prophase?
Chromosomes condense, spindle fibers form
Prophase is the first stage of mitosis.
What happens during Metaphase?
Chromosomes align at the cell equator
Metaphase ensures proper chromosome separation.
What happens during Anaphase?
Sister chromatids separate and move to opposite poles
Anaphase is critical for equal distribution of genetic material.
What happens during Telophase?
Nuclear envelopes reform, chromosomes uncoil
Telophase marks the near end of mitosis.
What is Cytokinesis?
Division of the cytoplasm, forming two separate cells
Cytokinesis completes the cell division process.
What is Heredity?
The passing of traits from parents to offspring
Heredity is the basis of genetic inheritance.
What is a Karyotype?
A display of an individual’s chromosomes
Karyotypes are used to identify chromosomal abnormalities.
What are Homologous Chromosomes?
Pairs of chromosomes, one from each parent
Homologous chromosomes carry genes for the same traits.
What is an Allele?
A variant of a gene
Alleles can be dominant or recessive.
What is a Dominant Allele?
An allele that is expressed when present (e.g., AA or Aa)
Dominant alleles mask the effect of recessive alleles.
What is a Recessive Allele?
An allele that is only expressed when both copies are recessive (e.g., aa)
Recessive alleles require homozygosity to be expressed.
What is a Genotype?
The genetic makeup of an individual (e.g., AA, Aa, or aa)
The genotype determines the potential traits of an organism.
What is a Phenotype?
The physical expression of a genotype (e.g., brown eyes)
Phenotypes can be influenced by environmental factors.
What does Homozygous mean?
Having two identical alleles (AA or aa)
Homozygosity can affect trait expression.
What does Heterozygous mean?
Having two different alleles (Aa)
Heterozygous individuals may express dominant traits.
What is a Punnett Square?
A diagram used to predict genetic inheritance
Punnett squares are useful for visualizing allele combinations.
What are Sex-Linked Traits?
Traits controlled by genes on the X or Y chromosome
Sex-linked traits often exhibit different inheritance patterns in males and females.
