Biology Flashcards
(71 cards)
What are the common features of all living cells?
All living cells contain DNA, cytoplasm, ribosomes, and a plasma membrane.
These features are present in both prokaryotic and eukaryotic cells.
Who invented the microscope and when was it first used to see cells?
Robert Hooke invented the microscope in 1665.
He observed cells for the first time in tiny slivers of cork.
What is the limitation of light microscopes?
The wavelength of light is the limiting factor for light microscopes.
This restricts the detail that can be seen inside cells.
What is the advantage of electron microscopes over light microscopes?
Electron microscopes use electron beams with shorter wavelengths, allowing more detail to be seen.
However, they can only examine dead material.
What are 70S ribosomes and where are they found?
70S ribosomes are found in bacterial cells.
In contrast, plant and animal cells have 80S ribosomes.
What is the function of the plasma membrane?
The plasma membrane protects the cell from its surroundings and regulates movement of substances in and out of the cell.
It is a small, membrane-bound sac.
What is the structure and function of the rough endoplasmic reticulum (rER)?
The rER consists of a series of single, flattened sacs with ribosomes on the surface that make proteins.
It is enclosed by a membrane.
Describe the nucleus and its characteristics.
The nucleus is surrounded by a double membrane (envelope) with pores.
It contains dense DNA and protein.
What are centrioles and their role in the cell?
Centrioles are two hollow cylinders arranged at right angles to each other that make the spindle in cell division.
What is the function of the smooth endoplasmic reticulum (SER)?
The SER is a series of single, tubular sacs made of membrane where lipids are made.
It does not have ribosomes.
What is a lysosome and its primary function?
A lysosome is enclosed by a single membrane and contains digestive enzymes to destroy old organelles and pathogens.
What are the structural features of a mitochondrion?
Mitochondria are surrounded by a double membrane with an inner membrane folded into cristae and contain a jelly called the matrix.
They house 70S ribosomes and DNA and are the site of respiration.
What is the Golgi apparatus responsible for?
The Golgi apparatus modifies proteins and packages them in vesicles for transport.
It consists of a series of single, curved sacs.
Fill in the blank: The _______ is the fluid that fills a cell and is the site of many metabolic processes.
cytoplasm
What are prokaryotes?
Bacteria are prokaryotes, made of a single cell with no membrane-bound organelles.
What is a plasmid?
Double-stranded DNA in a circular structure that often contains additional genes aiding survival, such as antibiotic resistance or toxin-producing genes.
What is the function of a capsule in bacteria?
Protects cells from drying out, being engulfed by white blood cells, and helps cells to stick to surfaces.
What do ribosomes do?
Makes proteins.
What is the nucleoid?
Region where a single circular length of DNA is folded; carries all essential information.
What is the structure of the cell wall in bacteria?
Made of a long-chained molecule called peptidoglycan, composed of sugar and amino acids.
How do gram-negative bacteria differ from gram-positive bacteria regarding the gram stain?
Gram-negative bacteria do not retain the gram stain when washed with acetone and alcohol due to their outer layer.
Why do gram-positive bacteria retain the gram stain?
They have a thick peptidoglycan wall that absorbs the stain and do not have an outer wall.
What makes gram-negative bacteria more resistant to antibiotics?
They have a cell wall with an outer membrane, which protects them from antibiotics.
Fill in the blank: The thin peptidoglycan cell wall of gram-negative bacteria is stained _______.
red
