Biology Unit Test Flashcards
(21 cards)
What does DNA stand for?
Deoxyribonucleic acid
DNA encodes genetic instructions for the development and functioning of living organisms.
What is the shape of the DNA molecule?
Double helix
The structure was first described by Watson and Crick in 1953.
What are the components of a nucleotide?
Nitrogenous base, sugar molecule, phosphate group
Each nucleotide is a building block of DNA.
Which nitrogenous bases pair together in DNA?
- Adenine (A) with Thymine (T)
- Cytosine (C) with Guanine (G)
A and T are connected by two hydrogen bonds, C and G by three.
How many pairs of chromosomes do humans have?
23 pairs (46 total)
This includes 44 autosomes and 2 sex chromosomes.
What is a karyotype?
A visual representation of an individual’s chromosomes
It is used to identify genetic disorders.
What is mitosis?
The process by which a single cell divides to produce two genetically identical diploid cells
Mitosis is essential for growth, repair, and asexual reproduction.
What is meiosis?
A specialized form of cell division that produces gametes with half the number of chromosomes
It introduces genetic diversity through crossing over and independent assortment.
What are genes?
Segments of DNA that code for specific traits
Humans have approximately 20,000 genes across 23 chromosomes.
What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup, while phenotype describes observable characteristics
Environmental interactions can influence phenotype.
What is the central dogma of molecular biology?
DNA → RNA → Protein
This describes the flow of genetic information.
What occurs during transcription?
A segment of DNA is copied into messenger RNA (mRNA)
This process occurs in the nucleus.
What is the role of ribosomes in protein synthesis?
Ribosomes read mRNA sequences to synthesize proteins
They facilitate the translation process.
What are codons?
Sequences of three nucleotides in mRNA that correspond to specific amino acids
Codons are essential for protein synthesis.
What is codominance?
When both alleles are expressed equally in a heterozygous individual
This results in a phenotype that displays both traits.
What is incomplete dominance?
A blending of traits where the phenotype is an intermediate between two homozygous phenotypes
Example: red and white flowers producing pink flowers.
What are mutations?
Changes in the DNA sequence that can lead to variations in traits
They can be caused by environmental factors or errors during DNA replication.
What is adaptive radiation?
A key type of speciation where a common ancestor diversifies into various species due to geographical barriers
Example: Darwin’s finches.
What are GMOs?
Organisms with altered DNA to exhibit new traits
Examples include pest-resistant crops.
What is gene therapy?
A technique aimed at treating genetic disorders by inserting healthy genes into a patient’s cells
It holds promise for conditions like cystic fibrosis.
What is forensic genetics?
The use of DNA analysis to solve crimes and identify individuals
Techniques like DNA fingerprinting are employed.
