cells

Question 1

Define a living cell

Answer 1

• cells are the fundamental unit of all living things on earth
• they take nutrients and energy from their
  surroundings and make copies of themselves

Question 2

State the range of cell sizes, from the smallest to the largest known cells?

Answer 2

small cell: mycoplasma genitalium - 0.3um , 10^-14
big cell: ostrich cell -  20cm - 2kg
fancy cell: diatom - 100um
RBC - round , biconcave 
WBC - amoeboid
nerve cells -  branched long
mesophyls - round and oval 
epithelial- long and narrow

Question 3

Discuss the key universal features of all living cells?

Answer 3

cells on earth

• all cells are sourrounded by a plasma membrane
• Cells exchange molecules with their surroundings
• cell communicate
• All cells store their hereditary information as DNA
• The DNA fragment corresponding to one protein is one gene
• Cells translate RNA into protein in the same way

Question 4

what are the components in eukaryotic cell

Answer 4

• golgi apparaturs
• smooth, rough EPR
• nucleus
• nucleolus
• ribosomes
• cytoplasm
• plasma membrane
• nuclear envelope
• secretory vesicles
• lysosome
• centrosome
• mitochondrion
• centriole

Question 5

Explain why cells from all domains of life have fundamental features in common? and explain how cells are made from simple building blocks

Answer 5

Taxonomy: “academic discipline of defining groups of biological organisms on the basis of shared characteristics
Phylogenetics: “study of evolutionary relationships among groups of organisms

- Cells are made from a few simple building blocks
building blocks vs larger units
- sugar -- polysachharides
- amino acid - protein 
- nucleotides - nucleic acid
- fatty acid - lipids

Question 6

Describe in a schematic manner the structure of DNA, RNA and proteins?

Answer 6

DNA

• sugar phosphate
• nitrogenous base
• phosphate
• deoxyribose

RNA

• uracil
• cytosine
• adenine
• guanine
• ribose

Question 7

Explain in broad outline the steps by which genetic information in DNA is transcribed into RNA and then translated into protein?

Answer 7

Transcription:
-a molecule of mRNA is made in the nucleus:
• The hydrogen bonds between the complementary bases break and the DNA uncoils
thus separating the two strands
• One of the DNA strands is used as a template by RNA polymerase to make the
mRNA molecule
• Free nucleotides line up by complementary base pairing and adjacent nucleotides
are joined by phosphodiester bonds made by RNA polymerase thus forming a single
stranded molecule of mRNA
• mRNA then moves out of the nucleus through a pore and attaches to a ribosome in
the cytoplasm which is the site of next stage of protein synthesis called translation
Translation:
• mRNA attaches to a ribosome and transfer RNA collects amino acids from the
cytoplasm and carries them to the ribosome. tRNA is a single stranded molecule
with a binding site at one end thus it can only carry one type of amino acid, and a
triplet of bases at the other
• tRNA attaches itself to mRNA by complementary base pairing – two molecules
attach to mRNA at a time
• The amino acids attached to two tRNA molecules join by a peptide bond and then
tRNA molecules detach themselves from the amino acids, leaving them behind
• This process is repeated thus leading to the formation of a polypeptide chain until a
stop codon is reached on mRNA and ends the process of protein synthesis

Question 8

Explain the concept of life as “a pattern in flux” ?

Answer 8

as the number of days increase water replacement in body is decreased due to your body using water to maintain its temperature, remove waste, and lubricate your joints

Question 9

Define the concept of homeostasis

Answer 9

the ability or tendency of an organism or
cell to maintain internal equilibrium by adjusting its
physiological processes.”