chapter 2 Flashcards
molecules, cells, and theories
four major classes of biomolecules
proteins
carbohydrates
lipids
nucleic acids
biomolecules primarily consist of four different atoms
CHON
two main types of proteins
- structural: form structural components of the cell
- enzymes: speed and regulate biochemistry
what causes a protein to fold?
occurs spontaneously, based on amino acid sequence ; environmental factors also affect conformation
four levels of protein structure
primary
secondary
tertiary
quaternary
carbohydrates
- sugars and sugar polymers
- mono and poly
- function: energy and structure
lipids
- molecules that are mostly H and C
- functions: energy source, structural, cholesterol
function of nucleic acids
information storage
energy source
central dogma
dna - rna - protein
dna organization
organized into distinct units called chromosomes
chromatin (large)
- all genetic material in nucleus
- 3 x 109 base pairs
chromosome (medium)
- dna/protein structures carrying genes
- 1 x 106/7 nucleotides per chromosome
- 23 pairs in humans
gene (small)
- nucleotide sequence of dna that controls one hereditary characteristic of an organism
-encodes an rna molecule
heterochromatin
tightly packed chromatin, not available for gene expression
cell membrane
- barrier to maintain the cell’s internal chemistry
- phospholipids and diverse proteins
mitochrondria
use sugar, fat and protein to make atp
ER and golgi
allow for the manufacture and secretion of biomolecules
cytoskeleton
gives shape and support
intercellular materials
- amorphous: vary in their H2O/protein content
- fibers: collagen and elastin
why do cells divide?
- growth/development
- repair/regeneration
- reproduction
cells reproduce via mitosis
- chromosomes are duplicated by dna replication
- pulled apart by the cytoskeleton, which pinches cell in half
do all cells divide?
frequency of mitosis depends on cell type : continous, based on need, and rare/never
evolution
- the change in genetic composition of a population from generation to generation, that over time brings about new species
- occurs by mutation
- proceeds by natural selection
three criteria for valid theory
- changes addressed must occur commonly in all members of species
- process must be progressive
- process must lead to organ dysfunctions that ultimately lead to failure of organ
three main groups of theories
- aging results from wearing out of organ
- aging results from nonreversible chemical changes within cells that alter its functioning
- aging is programmed by a biological clock, located in center of each cell
theories of aging
genetic
rate of living
free radical
mitochondrial
clinker
cross linkage
immune deficiency
wear and tear
genetic theories
death gene
telomere
somatic mutation
faulty dna repair
error catastrophe
death gene theory
a set of genes activates late in life, and tells the body to deteriorate and die
telomere theory
shortening of telomeres affects the expression of certain genes
somatic mutation theory
harmful factors may injure genes (radiation)
faulty dna repair theory
dna damage is repaired early in life, overtime repair mechanisms begin to fail
error catastrophe (disproven)
damage to rna and protein result in biological aging
rate of living theory (disproven)
metabolic rate is directly related to the rate of aging, and inversely related to life span
free radical theory
an atom/molecule with an odd number of e-s-an unpaired electron
- highly reactive, occur naturally, eliminated by antioxidants
mitochondrial theory
mitochondrial activity and damage cause aging
clinker theory
waste products accumulate in cells over time
cross linkage theory
post-translational modification to proteins resulting in irreversible changes to their structure, occurring over time. affects flexibility and functioning
- due to free radicals and glucose
glycation
covalent joining of a sugar to a protein via particular amino acids
immune deficiency theory
over time, immune system begins to damage your tissues (autoimmunity)
wear and tear theory
an accumulation of injuries adversely affects the tissues/bodies
