A Tour Of Cells

Question 1

Cell wall

Answer 1

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important components of cell walls

Question 2

Capsule

Answer 2

In many prokaryotes, a dense and well-defined layer of polysaccharide or protein that surrounds the cell wall and is sticky, protecting the cell and enabling it to adhere to substrates or other cells

Question 3

Cytosol

Answer 3

The semi fluid portion of the cytoplasm

Question 4

Peroxisome

Answer 4

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2)

Question 5

Plasma membrane

Answer 5

The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition

Question 6

Fimbria (plural, fimbriae)

Answer 6

A short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells

Question 7

Chloroplast

Answer 7

An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water

Question 8

Cytoplasm

Answer 8

The contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus

Question 9

Mitochondrian

Answer 9

An organelle in eukaryote cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesise ATP

Question 10

Nucleoid

Answer 10

A non-membrane bounded region in a prokaryotic cell where the DNA is concentrated

Question 11

Nucleolus

Answer 11

A specialised structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly.

Question 12

Nucleosome

Answer 12

The basic, bead-like unit of DNA packing in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone

Question 13

Nucleus

Answer 13

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin

Question 14

Nuclear lamina

Answer 14

A netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus

Question 15

Nuclear envelope

Answer 15

In a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum

Question 16

Flagellum (plural, flagella)

Answer 16

A long cellular appendage specialised for locomotion. Like motile cilla, eukaryotic flagella have a core with nine outer doublet microtubules and two inner single microtubules ensheathed in an extension of the plasma membrane. Prokaryotic flagella have a different structure

Question 17

Histone

Answer 17

A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure

Question 18

Organelle

Answer 18

Any of several membrane-enclosed structures with specialised functions, suspended in the cytosol of eukaryotic cells