Topic 1: Biochemistry of Life (Nutrients and Nutrition) Flashcards
Why are nutrients so important from a cellular perspective?
Cells continuously regenerate/repair/produce and they need building blocks (nutrients) to do so
Give an exemple of a nutrient influencing gene expression. How does it work?
Lactose and the lac Operon;
Absence of lactose –> repressor (normally produced) binds to promoter region => LacO cannot be transcribed
Presence of lactose –> induction (turns on) a gene that produces an inducer. It will bind to repressor preventing the repressor to bind to lacO –> lac Operon can now be transcribed
How can a dietary constituent regulate transcription (scheme) and how do we ensure a permanent change?
by interacting with genes which will then by
a) Direct regulation: Inc. or Dec. in the transcription of genes –> change in mRNAs –> change in Proteins (will induce an incease or decreases in specific cellular activity)
b) Indirect regulation (fast change, but temporary): produce a Physiological Modulation (insulin –> signaling cascade) which will produce a Secondary Mediator who will then interact again with genes to then Regulate transcription –>…
To ensure a permanent change, need to change genes (regulate transcription)
How can nutrients specifically regulate gene expression in a cell (4)
- Bind to receptor on membrane which will produce a signal, affecting gene expression
- Are transported in the cell and bind to transcription factors (Nuclear receptors), affecting gene expression
- Induce DNA methylation, affecting gene expression
- Bind directly to produced protein and modifies it’s activity (activate/deactivate)
What are functional groups?
Reorganized elements that have specific properties
What else to cells need to grow (bulk up) other than proteins? What specific protein is central to this process; what does it do? By what (3) ways is this central protein influenced?
1) Lipids: need to increase membrane to have a bigger volume
2) mTORC1: it basically controls the synthesis of proteins and lipids (through SREBP1). mTROC1 is influenced by nutrients (amino acids and glucose intake), cellular energy status (AMPK) and growth factor (Akt)
How is SREBP activity regulated?
- In low [sterol], SREBP (found on the ER) is transported into the Golgi to be transformed into a nuclear factor which will target genes responsible for cholesterol and fatty acid biosynthesis
- In high [sterol], cholesterol binds to SREBP, preventing it to leave ER => no inc. in sterol production
Name three carbohydrates and where we can find them
Glycogen (liver of animals)
Cellulose (cell wall of plant cells)
Starch (in plant cells)
When it come to digestion, what influences changes in blood sugar for carbohydrates?
A difference in their complexity (glycemic index)
What is important for proteins to function?
They need to retain their shape; A change in shape can induces a loss in function
Why is water important?
It is the medium in which chemical reactions occur
How can protein become hypoallergenic? What is their use (2)?
By changing their shape or cutting them (hydrolyzing) to smaller pieces. They are used in infant formula; Gives glutamic acid (flavor enhancer, responsible for umami taste, neurotransmitter)
What is PKU? What are it’s effects?
Phenylketonuria: gene variation that alters phenylalanine enzyme or Phe enzyme activity. Results in increase [Phe] in blood –> high [Phe] in brain =>
decreases: synaptic transmission, protein synthesis, neurotransmitter synthesis
damages myelin
What should not be eaten if have PKU?
If have PKU, want to watch Phe consumption; Aspartame should not be consumed since it is composed of aspartic acid and phenylalanine.
What are the 4 types of fatty acids whose name depends on their length?
Short chain (2-6C) Medium chain (8-10C) Long chain (12-20C) Very long chain (>20C)
