dna structure Flashcards
. DNA Definition
DNA is a nucleic acid that stores genetic information and controls cellular activities, including protein synthesis.
DNA Structure
DNA consists of nucleotides, which have three components: phosphate group, deoxyribose sugar, and nitrogenous base.
Nucleotide Components
Nucleotides are made up of a phosphate group, deoxyribose sugar, and one of four nitrogenous bases (adenine, thymine, guanine, cytosine).
Complementary Base Pairing
Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C) through weak hydrogen bonds.
Double Helix
DNA has a double helix structure, where two strands of nucleotides wind around each other. Discovered by Watson and Crick.
Chromosomes
DNA is organized into chromosomes, which are condensed structures containing genes. Humans have 46 chromosomes (23 pairs).
Chromatin Network
DNA exists in a less condensed form as chromatin in the cell nucleus, except during cell division or replication.
Genes
Genes are segments of DNA that code for proteins and are the units of hereditary information.
Sugar-Phosphate Backbone
The phosphate groups and deoxyribose sugars form the backbone of DNA, connecting the nucleotides.
Purines and Pyrimidines
Adenine and Guanine are purine bases with double rings, while Thymine and Cytosine are pyrimidine bases with single rings.
DNA Replication
DNA replication is the process of copying DNA, ensuring genetic information is passed to daughter cells during cell division.
Hereditary Information
DNA carries hereditary information in genes, influencing an organism’s traits and characteristics.
Protein Synthesis
DNA provides instructions for protein synthesis, vital for growth, development, and cellular functions.
Complementary Base Pairing
Adenine pairs with Thymine, and Guanine pairs with Cytosine through hydrogen bonds, ensuring accurate DNA replication and transcription.
DNA Shape
The DNA molecule has a double helix structure with complementary base pairs forming rungs, discovered by Watson and Crick.
Nucleotide Function
Nucleotides are the monomers of DNA, linked together to form a DNA strand through phosphodiester bonds.
Weak Hydrogen Bonds
Hydrogen bonds between complementary bases (A-T, G-C) are weak, allowing DNA strands to be separated during replication and transcription.
Chromosome Structure
Chromosomes consist of condensed DNA strands, including two chromatids joined by a centromere.
DNA Code
DNA’s sequence of nucleotides encodes the genetic information necessary for an organism’s traits and functions.
Genetic Replication
DNA replication involves unwinding the double helix, synthesizing new complementary strands using existing strands as templates, and forming two identical DNA molecules.
DNA Function
DNA carries hereditary information, guides protein synthesis, and ensures genetic information is passed to offspring through replication.
DNA Replication Process
DNA replication involves the separation of DNA strands, primer attachment, complementary nucleotide addition, and DNA strand elongation.
Genetic Variation
Genetic variation arises from differences in DNA sequences, contributing to diversity within and among species.
Chromatin vs. Chromosome
Chromatin is the relaxed, less-condensed form of DNA, while chromosomes are tightly coiled structures seen during cell division.
Nucleotide Pairing Rules
Adenine pairs with Thymine, forming two hydrogen bonds, while Guanine pairs with Cytosine, forming three hydrogen bonds.
DNA Helicase
DNA helicase unwinds the double helix during replication, creating single-stranded regions for nucleotide pairing.
Semiconservative Replication
DNA replication is semiconservative, where each new DNA molecule consists of one old strand and one newly synthesized strand.
Role of DNA in Heredity
DNA is the molecule of heredity, passing genetic information from parents to offspring through reproduction.
Protein Synthesis Steps
Protein synthesis involves transcription (DNA to RNA) and translation (RNA to protein), guided by the genetic code.
Central Dogma
The central dogma of molecular biology describes the flow of genetic information: DNA to RNA to protein.
