Quick Review Flashcards - Click to flip and test your knowledge!
Question
What is the complex of DNA and proteins called when a cell is in a non-dividing state?
Answer
Chromatin
Question
Chromosomes are formed by the condensation of _____ during cell division.
Answer
chromatin fibres
Question
Who was the German scientist that first studied chromosomes in animal cells in 1882?
Answer
Walther Flemming
Question
The term 'mitosis' literally translates to which English word?
Answer
"thread"
Question
Chromatin material is composed of approximately 40% _____ and 60% histones.
Answer
DNA (deoxyribonucleic acid)
Question
Which scientist first studied the shape of the DNA molecule using X-ray crystallography in 1953?
Answer
Rosalind Franklin
Question
Which two scientists proposed the double-stranded helical structure of DNA in 1953?
Answer
Watson and Crick
Question
What are the repeating chemical units that compose a single DNA strand?
Answer
Nucleotides
Question
Name the three specific components that make up a single nucleotide.
Answer
Phosphate group, pentose sugar, and a nitrogenous base
Question
In the DNA 'ladder' arrangement, what components form the 'rungs'?
Answer
Nitrogenous bases
Question
Which nitrogenous base always pairs with Adenine in a DNA molecule?
Answer
Thymine ($A = T$)
Question
How many hydrogen bonds connect Guanine and Cytosine in a DNA double helix?
Answer
Three hydrogen bonds ($G \equiv C$)
Question
List the two nitrogenous bases classified as Purines.
Answer
Adenine (A) and Guanine (G)
Question
Which pyrimidine base is found in RNA but absent in DNA?
Answer
Uracil (U)
Question
What is the structural unit consisting of a DNA strand wound around a core of eight histone proteins?
Answer
Nucleosome
Question
Approximately how many meters of DNA are contained within the nucleus of a single human cell?
Answer
$2$ metres
Question
The diameter of a human cell nucleus is approximately $6\ \mu m$, while the DNA length is $2\ m$; how is this fit achieved?
Answer
Through coiling and super-coiling of chromatin fibres.
Question
What is the point of attachment where two sister chromatids are joined together?
Answer
Centromere
Question
Term: Gene
Answer
Definition: A specific sequence of nucleotides on a chromosome that encodes a particular protein.
Question
Which chromosomal region serves as the attachment site for spindle fibres during cell division?
Answer
Centromere
Question
What are the two identical vertical halves of a duplicated chromosome called?
Answer
Sister chromatids
Question
Approximately what percentage of total DNA is considered 'non-functional' and used for DNA fingerprinting?
Answer
$99\%$
Question
The organized, predictable series of events from one cell division to the next is known as the _____.
Answer
cell cycle
Question
Name the two primary phases that constitute the cell cycle.
Answer
Interphase and the dividing phase (M-phase)
Question
What are the three sub-phases of Interphase in chronological order?
Answer
First growth phase ($G_1$), synthesis phase ($S$), and second growth phase ($G_2$)
Question
During which specific sub-phase of Interphase does DNA replication occur?
Answer
$S$ phase (Synthesis phase)
Question
In the $G_1$ phase of the cell cycle, which two organelles divide because they possess their own DNA?
Answer
Mitochondria and chloroplasts
Question
What describes the state of a cell in the $G_0$ or 'resting' phase ($R$)?
Answer
The cell has withdrawn from the cell cycle and is not preparing for division.
Question
What is the typical lifespan of a human red blood cell before it must be replaced?
Answer
About $120$ days
Question
Which human cell type is never replaced once it dies after formation in the embryo?
Answer
Nerve cells (of the brain and cerebral cortex)
Question
Term: Karyokinesis
Answer
Definition: The division of the cell nucleus during mitosis.
Question
Term: Cytokinesis
Answer
Definition: The division of the cytoplasm resulting in two daughter cells.
Question
List the four stages of karyokinesis in their correct sequence.
Answer
Prophase, Metaphase, Anaphase, and Telophase
Question
During which phase of mitosis do centrioles move to opposite poles and form asters in animal cells?
Answer
Prophase
Question
What occurs to the nuclear membrane and nucleolus during late prophase?
Answer
They disappear.
Question
In which phase of mitosis do chromosomes align along the equatorial plane of the cell?
Answer
Metaphase
Question
What critical event involving the centromere occurs during Anaphase?
Answer
The centromere divides, allowing sister chromatids to separate.
Question
During which phase of mitosis do the chromatids thin out and turn back into a network of chromatin threads?
Answer
Telophase
Question
How does cytokinesis differ between animal cells and plant cells?
Answer
Animal cells use a cleavage furrow; plant cells form a cell plate.
Question
In plant cells, cytokinesis begins at the centre and proceeds towards the periphery via a _____.
Answer
cell plate
Question
In animal cells, cytokinesis begins at the periphery and proceeds towards the centre via a _____.
Answer
cleavage furrow
Question
What are the four main biological needs for producing new cells via mitosis?
Answer
Growth, replacement, repair, and asexual reproduction
Question
Which type of cell division maintains the same number of chromosomes in the daughter cells as the parent cell?
Answer
Mitosis
Question
Term: Meiosis
Answer
Definition: A reduction division where the chromosome number is halved to produce haploid gametes.
Question
What is the diploid ($2n$) number of chromosomes in a normal human body cell?
Answer
$46$ (or $23$ pairs)
Question
How many chromosomes are found in a human sperm or egg cell?
Answer
$23$ (haploid)
Question
Term: Crossing over
Answer
Definition: The exchange of genetic material between non-sister chromatids of a pair of homologous chromosomes during meiosis.
Question
What is the name of the X-shaped structure formed when non-sister chromatids pair during crossing over?
Answer
Chiasma
Question
How many daughter cells are produced at the completion of a full meiotic division?
Answer
Four daughter cells
Question
In which plant organs does meiosis occur to produce pollen grains and ovules?
Answer
Anthers and ovary
Question
What describes the genetic relationship between daughter cells produced by mitosis?
Answer
They are genetically identical to each other and the parent cell.
Question
What describes the genetic relationship between daughter cells produced by meiosis?
Answer
They are genetically unique due to random assortment and crossing over.
Question
Which phase of mitosis is essentially the reverse of prophase regarding the nuclear membrane and chromosome density?
Answer
Telophase
Question
What determines whether a tumour resulting from uncontrolled cell division is cancerous or not?
Answer
Whether the cell growth is non-stop and malignant.
Question
The radiating microtubule threads that appear between centrioles in animal cells are called _____.
Answer
spindle fibres
Question
What is the biological significance of the chromosome number being halved during meiosis?
Answer
It ensures the diploid number ($2n$) is restored upon fertilisation.
Question
Which scientist's X-ray data was used by Watson and Crick to determine the DNA structure?
Answer
Rosalind Franklin
Question
The basic structural and functional unit of a chromosome is the _____.
Answer
nucleosome
Question
The basic structural and functional unit of DNA or RNA is the _____.
Answer
nucleotide
Question
In which specific plant tissue does active mitotic division occur for growth in girth and length?
Answer
Meristematic tissue