Cellular Physiology 2 - Cytoplasm, Nucleus & Genetics Flashcards
What is the internal environment?
the extracellular fluid in which the cells live
What are organelles?
Smaller parts of the cell with specific
functions
What is cytoplasm?
Content of the cell outside the nucleus but inside the cell
membrane (area within the membrane)
No genetic material
Houses organelles
What is cytosol?
Complex mixture of cytoskeleton, filaments, dissolved
molecules
What is the cytoskeleton?
Dense network of protein fibres running through the cytoplasm
Give a cell its shape & provide a basis for movement
Microtubules - Made from tubulin
Microfilaments - Made from actin
Intermediate fibres
What are cilia?
Thread-like projections that beat in a regular
fashion to create currents that sweep materials along
What are flagella?
Extend to the rear of a cell and push it forward by
snakelike wriggling, or stick out in front and draw it along
What is the Endoplasmic reticulum?
The internal delivery system of the cell
2 types of endoplasmic reticulum
Rough ER - Rough appearance due to ribosomes
Makes proteins
Smooth ER – Smooth appearance (No ribosomes)
Makes fats or lipids
What are Ribosomes?
Organelles that help in the synthesise proteins
Some ribosomes are found in the cytoplasm - Most are attached to the endoplasmic reticulum
2 subunits – Required for protein synthesis
Large subunit
Small subunit
Units dock together to
make proteins from RNA
What are golgi apparatus?
Receives protein & lipid-filled vesicles from endoplasmic reticulum, packages, processes, and
distributes them within the cell or for export out of the cell
Enclose digestive enzymes into
membranes to form lysosomes
What are lysosomes?
Break down food (powerful digestive enzymes) into particles the rest of the cell can use and to destroy
old cells or invaders
What are Mitochondrion?
Organelle responsible for the generation energy, i.e. ATP
Contains DNA
Can replicate themselves
Bound by a double membrane
What is the nucleus?
Separates the genetic material (DNA) from the rest of the cell
It is the largest organelle of the cell
DNA is a blueprint or code for making proteins
What is DNA?
Deoxyribonucleic acid – Carrier of genetic information that form chromosomes
Double helix shape – 2 chains of nucleotides
The two strands are antiparallel
The backbone of the DNA molecule is composed
of alternating phosphate groups & sugars
What is the function of DNA?
Code for proteins
Storage of genetic information
Self-duplication & inheritance
Expression of the genetic message
Information is encoded in the order of the nitrogenous bases I.E?
nucleobases
Name the 2 purines.
Adenine and Guanine
Name the 2 Pyrimidines.
Thymine and Cytosine
What do purines and Pyrimidines form part of?
a nucleotide
Purines pair with what?
Pyrimidines
Nucleotides form the structural units of what?
DNA & RNA
What does Nucleotide pairing do?
Pairing creates the DNA coding sequence
Purines pair with pyrimidines, but how?
Paired via hydrogen bonds
What is a genome?
The complete set of genetic information in an organism
What are genes?
Sequence of nucleotides in DNA
What is Ribonucleic acid (RNA)?
Single-stranded | Coding/decoding & regulation/expression of genes
What is Messenger RNA (mRNA)?
Replicates the DNA’s genetic code
What is Transfer RNA (tRNA)?
Reads the strand of mRNA and translates it into a strand of amino acids
What is Ribosomal RNA (rRNA)?
Makes polypeptides (assemblies of amino acids) that go to make up proteins
In protein synthesis, what is transcription?
Base triplets in DNA serve as template to copy information into a complimentary sequence of codons
1. Promoter - Nucleotide sequence that begins transcription
2. Transcription - Complimentary bases pair
3. Termination Nucleotide sequence that ends transcription
In protein synthesis, what is translation?
Nucleotide sequence in mRNA specifies the amino acid sequence of a protein
Large sub-unit of ribosome has
2 binding sites for TRNA – A-site & P-site
Small sub-unit of ribosome has
binding site for mRNA
What are the 3 parts of translation?
Initiation, Elongation and Termination
In translation, what is Initiation?
mRNA binds to small ribosomal sub-unit
Initiator tRNA binds to start codon (AUG)
on mRNA (not pictured)
tRNA anticodon (UAC) attaches to
mRNA codon (AUG)
Large ribosomal sub-unit attaches to
small ribosomal sub-unit
Initiator tRNA fits into P-site
In translation, what is Elongation?
Anticodon of incoming tRNA pairs with
next codon at A-site
Aino acid on tRNA at P-site form peptide
bond with amino acid at A site
tRNA at P-site leaves ribosome
Ribosome shifts by one codon
tRNA previously in A-site now in P-site &
allows another tRNA to bind to the
exposed A-site
In translation, what is Termination?
Protein synthesis stops when stop codon
enters A-site
Completed protein detaches from the
final tRNA
Ribosome splits into small & large subunits
What are telomeres?
DNA sequence found only at the tips of each chromosome
Each cell cycle division shortens telomeres
Ageing can cause telomeres to erode, including some functional components
of the chromosome
Shortening of telomeres contributes to cell death
Individuals who experience high levels of stress have shorter telomere length
What are free radicals?
Unstable molecules which produce oxidative damage by stealing an electron from a stable cell
Name 2 clinical ageing disorders.
Progeria
Werner Syndrome
What are some causes of cancer?
Carcinogens
Environmental agents (e.g. radiation, pollution) | Chemical agents (e.g. air, food & water)
Oncogenes
Cancer causing genes (e.g. ras gene family)
Oncogenic virus
Viruses that only reproduce when inside the cells they infect (e.g. HPV that causes almost
all cervical cancers in women)
Name 2 local methods of cancer therapy
Surgery and radiation
Name 3 systemic methods of cancer therapy
Chemotherapy
Hormone Therapy
Targeted therapy
What promotes a gradual reduction in cell function?
Ageing
What is a group of diseases characterised by uncontrolled or abnormal cell proliferation
Cancer
