Biology 1 Flashcards
Autolysis
Process of cell death initiated by lysosomes selectively choosing to when to release hydrolytic enzymes (suicide. e.g.: If DNA is damaged)
Microbodies
Peroxisomes and glyoxysomes
Glyoxysomes
convert fats into usable sugars (fuel); important in germinating plants until plant can make its own energy via photosynthesis.
Centriole
cylindrical structure composed of 9 bundles of 3 microtubules each. Animals cells have a pair oriented at right angles of each other; organizes spindle fibers during mitosis; form “highway system” in cell
Cell Theory
- All living things are composed of cells.
- The cell is the basic functional unit of life.
- Cells arise only from pre-existing cells.
- Cells carry genetic information in the form of DNA (passed on from parent to daughter cell).
Prokaryotic vs Eukaryotic ribosomal subunit weight
Prokaryotes: 30S and 50S Eukaryotes: 40s and 60s
Key Features of Enzymes
- Lower Ea (activation energy)
- Increase RATE of the reaction
- Do not alter Keq (equilibrium constant)
- Are not changed/consumed in reaction (appear in products and reactants)
- Are pH and temp sensitive: with optimal activity at specific pH ranges and temps
- Are specific for a particular reaction or class of reactions.
apoptosis
mito can release some of the enzymes in the electron transport chain during the process of programmed cell death
endosymbiotic theory
Water movement across semi-permeable membrane
- Mnemonic*
- Notice how the O in hyp-O-toniclooks like a swollen cell.*
Pinocytosis
endocytosis of fluids and dissolved particles
phagocytosis
ingestion of large solids such as bacteria. Often there will be a receptor to which substrates bind to induce ingestion.
4 Tissue types
EPITHELIAL TISSUE
These tissues cover the body and line its cavities; they provide a means for protection against invasion and desiccation. Epithelium is also involved in absorption, secretion, and sensation.
CONNECTIVE TISSUE
Connective tissue supports the body and provides a framework for higher-level interactions. Bone, cartilage, tendons, ligaments, adipose tissue, and blood are all connective tissues.
NERVOUS TISSUE
Neurons are the primary cells in nervous tissue. They make use of electrochemical gradients to allow for cellular signaling and the coordinated control of multiple tissues, organs, and organ systems.
MUSCLE TISSUE
There are three types of muscle tissue: skeletal, smooth, and cardiac. Whereas each serves a specific function (which we will discuss in Chapter 6), they all exhibit great contractile ability and strength.
Key Features of Enzymes
holoenzymes
Enzymes with their cofactors
Michaelis-Menten kinetics
We can assess an enzyme’s affinity for a substrate by noting the Km. A low Km reflects a high affinity for the substrate (low [S] required for 50% enzyme saturation). Conversely, a high Kmreflects a low affinity of the enzyme for the substrate.
EFFECTS OF TEMPERATURE on enzyme rates
Enzyme-catalyzed reactions tend to double in rate for every 10° C increase in temperature until the optimum temperature is reached; for the human body, this is 37° C. After this, activity falls off sharply, as the enzyme will denature at higher temperature
Reversible Inhibition
Irreversible Inhibition
active site is made permanently unavailable, or the enzyme is permanently altered.
zymogens
- secreted as inactive enzymes
- contain a catalytic (active) domain and regulatory domain.
- The regulatory domain must be either removed or altered to expose the active site.
- Apoptotic enzymes (caspases) exhibit similar regulation.
Thermodynamics and Kinetics (Summary)
- Endothermic reactions absorb energy; Δ H is positive
- Exothermic reactions emit energy; Δ H is negative
- Enzymes, as biological catalysts, are unchanged by the reaction and are reusable
- Enzymes lower the activation energy necessary for biological reactions
Enzymes do not alter the free energy (Δ G) or enthalpy (Δ H) change that accompanies the reaction nor the final equilibrium position; rather, they change the rate (kinetics) at which equilibrium is reached
Oxidized and Reduced forms of Electron Carriers
GLYCOLYSIS
Metabolic Map
The relationship of the three major energy sources
Total ATP generated (by glucose catabolism)
36 ATP (38 in prokaryotes)
Pyruvate decarboxylation
Pyruvate loses a CO2 group and the remaining acetyl group forms acetyl-CoA for use in the Krebs cycle
Meiosis vs Mitosis (key features)
Male Reproductive Anatomy
In males, the primitive gonads develop into the testes. The testes have two functional components: theseminiferous tubules and the interstitial cells (cells of Leydig). Sperm are produced in the highly coiled seminiferous tubules, where they are nourished by Sertoli cells. The cells of Leydig secretetestosterone and other male sex hormones (androgens). The testes are located in the scrotum, which is an external pouch that hangs below the penis and maintains a temperature 2° to 4° C lower than the body. This temperature differential is essential to proper sperm production.
As sperm mature, they are passed to the epididymis. They gain motility in the form of a flagellum and are then stored until ejaculation. During ejaculation, sperm travel through the ejaculatory duct andurethra, and exit the body through the penis (see Figure 4.9). In males, the reproductive and urinary systems share a common pathway; this is not the case in females.
As sperm passes through the reproductive tract, it is mixed with seminal fluid, which is produced through a joint effort by the seminal vesicles, prostate gland, and bulbourethral gland. The combination of sperm and seminal fluid is known as semen. The seminal vesicles contribute fructose to nourish sperm, and the prostate gland gives the fluid mildly alkaline properties so it will be able to survive the relative acidity of the female reproductive tract.
Spermatogenesis
spermatogonia (2n)
↓
1° spermatocytes (2n)
↓ meiosis I
2° spermatocytes (n)
↓ meiosis II
spermatids (n)
↓
spermatozoa (n)
Remember that spermatogenesis in males is a 1:4 division, whereas in females, oogenesis is 1:1.
Female Reproductive Anatomy
All of the female reproductive organs are internal, as opposed to external in the male (see Figure 4.11). The gonads, known as ovaries, produce estrogen and progesterone (much more on this when we discuss the endocrine system in Chapter 12). The ovaries are located below the digestive system in the pelvic cavity; each consists of thousands of follicles, which are multilayered sacs that contain, nourish, and protect immature ova. Between puberty and menopause, one egg per month will be released into the peritoneal sac, which lines the abdominal cavity. It then moves into the fallopian tube, or oviduct, which is lined with cilia to usher it along. The fallopian tubes are connected to the muscularuterus, which is the site of fetal development. The lower end of the uterus, known as the cervix, connects to the vaginal canal, where sperm is deposited during intercourse. The vagina is also the passageway through which childbirth occurs. The external female anatomy is known collectively as thevulva. As we mentioned earlier, unlike males, females have separate excretory and reproductive tracts.
Oogenesis
1° oocyte (2n)
↓ meiosis I
2° oocyte (n)
↓ fertilization
↓ meiosis II
ovum (n)
