1.5 and 1.6 Flashcards
What are ribosomes composed of?
Ribosomes are composed of ribonucleic acid (RNA) and proteins.
What is the size difference between eukaryotic and prokaryotic ribosomes?
Eukaryotic ribosomes are 80S, while prokaryotic ribosomes are 70S.
What are the subunits of 80S ribosomes in eukaryotes?
What are the subunits of 70S ribosomes in prokaryotes?
- The subunits of 80S ribosomes are 60S and 40S.
- The subunits of 70S ribosomes are 50S and 30S.
What does ‘S’ stand for in reference to ribosomes?
‘S’ stands for the sedimentation coefficient, which indirectly measures density and size.
What is the cytoskeleton?
The cytoskeleton is an elaborate network of protein structures in the cytoplasm.
What are the three types of filaments in the cytoskeleton?
The cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.
What functions are associated with the cytoskeleton?
The cytoskeleton is involved in mechanical support, cell motility, and maintaining the shape of the cell.
How do cilia and flagella differ in function?
Cilia work like oars, causing movement of the cell or surrounding fluid
Flagella are longer and responsible for cell movement.
What is the structure of cilia and flagella?
Cilia and flagella are covered with a plasma membrane and have a core called the axoneme.
The axoneme contains microtubules arranged in a 9+2 array, with nine doublets of peripheral microtubules and a pair of centrally located microtubules.
What connects the central tubules of the axoneme in cilia and flagella?
The central tubules are connected by bridges and enclosed by a central sheath, which is connected to one of the tubules of each peripheral doublet by a radial spoke.
There are nine radial spokes.
How do cilia and flagella emerge from the cell?
Both cilia and flagella emerge from a centriole-like structure called the basal body.
What is a centrosome?
The centrosome is an organelle that usually contains two cylindrical structures called centrioles, surrounded by amorphous pericentriolar materials.
How are the centrioles arranged in a centrosome?
The centrioles in a centrosome lie perpendicular to each other and have a cartwheel-like organization.
Each centriole is made up of nine evenly spaced peripheral fibrils of tubulin protein, arranged in triplets.
What is the hub and how is it connected in the centriole?
The hub is the proteinaceous central part of the proximal region of the centriole.
It is connected to the tubules of the peripheral triplets by radial spokes made of protein.
What are the functions of centrioles?
Centrioles serve as the basal bodies for cilia or flagella, and they are also involved in the formation of spindle fibers that make up the spindle apparatus during cell division in animal cells.
Who first described the nucleus as a cell organelle and in what year?
Robert Brown described the nucleus in 1831.
What are the components of the interphase nucleus?
The interphase nucleus contains chromatin, nuclear matrix, and one or more nucleoli.
What is the function of the nuclear envelope?
What does it consist of?
The nuclear envelope acts as a barrier between the materials inside the nucleus and the cytoplasm.
It consists of two parallel membranes with nuclear pores for the movement of RNA and protein molecules.
What is the function of nucleoli?
Nucleoli are sites for active ribosomal RNA synthesis and are more abundant in cells actively involved in protein synthesis.
What is the composition of chromatin?
Chromatin consists of DNA, histone proteins, non-histone proteins, and RNA.
What is the primary constriction of a chromosome called, and what is its function?
The primary constriction is called the centromere, which holds the two chromatids of a chromosome together during cell division.
How are chromosomes classified based on the position of the centromere?
Chromosomes can be classified as metacentric, sub-metacentric, acrocentric, or telocentric, depending on the position of the centromere.
What gives the appearance of a small fragment called a satellite in some chromosomes?
Some chromosomes have non-staining secondary constrictions that create a satellite-like structure.
