1.2 Flashcards
(20 cards)
What does totipotent means?
Ability to differentiate into any cell in the body
What is the function for the nucleus?
- control center of the cell
- houses genetic material
- Regulates expression of genes
- produces ribosomal subunits
What is the structure of the nucleus?
- Usually most prominent cellular feature
- most cells have one
- few cells have multiple nuclei (ie Skeletal muscle cells)
What is the nuclear envelope?
- A double membrane
- Opening in envelope called nuclear pores
- Continuous with the rough ER
What is the nucleolus?
- Spherical, dark body
- found within the nucleus
- not enclosed by a membrane
- Site of rRNA synthesis and initial ribosome assembly
- obvious in cells that are actively synthesising proteins
What is the structure of chromatin?
Compacted DNA wrapped around histone proteins
Packs into chromosomes
Euchromatin
Heterochromatin
Describe euchromation
Dispersed, lightly stained, ACTIVE cell
Describe Heterochromatin
- highly condensed, intensely stained, INACTIVE cell
Describe DNA
Deoxyribonucleic acid
Sugar base - deoxyribose
Double stranded
Describe RNA
Ribonucleic acid
Sugar base - Ribose
Single stranded
What is mRNA?
Messenger RNA
Encode amino acid sequences during translation
Describe the process of
DNA to RNA
- Occurs in the nucleus
- A specific fragment of DNA copied into a strand of messenger RNA
- mRNA enter the cytoplasm and sequence encodes for a specific amino acid chain
Describe the process of transcription
DNA uncoils
Gene sequence is exposed
MRNA strand is assembled by enzymes
Generated mRNA sequence is complementary to the DNA
What is tRNA?
Transfer RNA
Carry amino acid blocks during translation
What is rRNA?
Ribosomal RNA
Constitute ribosomes
What is the process of mRNA to a protein?
- Occurs in the cytoplasm
- mRNA is decoded by ribosomes
- Amino acids align to make a specific protein
What are the three sequence events in translation?
Initiation, elongation, termination
What occurs during initiation?
mRNA enters the cytoplasm and binds to a ribosome unit
tRNA delivers specific amino acids
What occurs during elongation?
Amino acids are linked to form a polypeptide chain (protein)
What occurs during termination?
Proteins are released and further modified
