BSC 2023 Study - E1

homeostasis

state of body equilibrium, where the body's internal environment remains relatively constant and within physiological limits

negative feedback

operates to reduce or eliminate the changes detected by the stimulus receptor; ex: sweating when cold

Cell Theory

major theory in biology that states:
1. cell is the basic unit of life
2. all living things are made up of cells
3. new cells arise only from pre-existing cells

What are the two categories of cells?

prokaryotic and eukaryotic

prokaryotes

cells that lack a membrane-bound nucleus and membranous organelles; ex: bacteria and archaea

eukaryotes

cells that have a membrane bound nucleus and membranous organelles; ex: animals, plants, fungi, and protists

plasma membrane

outer membrane that regulates what enters and leaves the cell; composed of a phospholipid bilayer with attached or embedded proteins

selectively permeable

membrane allows certain molecules to enter and exit

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

diffusion

movement of molecules or ions from a region of higher concentration to lower concentration; requires no energy (passive transport)

osmosis

diffusion of water across a selectively permeable membrane

tonicity

the osmotic characteristics of a solution across a particular membrane

isotonic solution

equal solute concentration in and outside of the cell; the cell stays the same

hypertonic solution

Solute concentration is greater than that inside the cell; cell loses water and shrivels (hyper/ADHD analogy)

hypotonic solution

Solute concentration is less than that inside the cell; cell gains water and bursts (hippo analogy)

0.9%

What is the NaCl concentration for red blood cells in homeostasis?

facilitated transport

Use of a plasma membrane carrier to move a substance into or out of a cell from higher to lower concentration; no energy required (passive transport)

active transport

Use of a plasma membrane carrier protein to move a molecule or ion from a region of lower concentration to one of higher concentration; it opposes equilibrium and requires energy (ATP)

metabolism

all chemical reactions that occur within a cell

enzymes

proteins that are capable of speeding up a specific chemical reaction by lowering the required activation energy

active site

surface of the enzyme where substrate binds and the reaction occurs

substrate

reactant in a reaction controlled by an enzyme

mitochondria

organelle with two membranes that carries out cellular respiration (converts chemical energy of glucose to chemical energy of ATP)

cristae

folded extensions of the inner membrane; where ATP production occurs

cristae

Where does ATP production occur in the mitochondria?

matrix

gel-like fluid of inner space surrounded by cristae in the mitochondria; contains enzymes for breaking down glucose products

intermembrane space

space between inner and out membrane of the mitochondria

cellular respiration

metabolic reactions that use energy primarily from carbohydrates (glucose) to produce ATP molecules

C6H12O6 + 6O2 -\> 6CO2 + 6H2O + ATP

What is the chemical equation for cellular respiration?

glucose + oxygen -\> carbon dioxide + water + energy

What is the word equation for cellular respiration?

glycolysis, citric acid cycle, electron transport chain

What are the three pathways involved in cellular respiration?

glycolysis

pathway of cellular respiration that entails the breakdown of glucose that occurs in the cytoplasm of the cell; splits glucose C6 into 2 pyruvates C3
-yields 2 molecules of ATP
-converts 2 molecules of NAD+ to NADH

nicotinamide adenine dinucleotide (NAD+)

a coenzyme that carries hydrogen and two electrons and is involved in cellular respiration (uncharged gift card analogy)

citric acid cycle (Kreb Cycle)

pathway of cellular respiration; aerobic process that occurs in the matrix of the mitochondria; pyruvate enters matrix and completes the breakdown of glucose
-produces 2 ATP per glucose molecule
-electrons and hydrogen are picked up by NAD+ as NADH

electron transport chain

pathway of cellular respiration; passage of electrons along a series of intermembrane-bound carrier molecules from a higher energy level to a lower energy level (slide energy analogy)
-hydrogen is moved to intermembrane space from matrix by active transport
-proton (hydrogen) gradient will yield 32 ATP

2

How much ATP is produced in glycolysis?

2

How much ATP is produced per glucose in the citric acid cycle?

32

How much ATP is produced after the electron transport chain?

fermentation

anaerobic process that enables NADH to pass off its hydrogen and electrons to pyruvate
-converts pyruvate to lactate and yields 2 ATP per glucose
-yeast fermentation produces alcohol and carbon dioxide

pyruvate

the output of the metabolism of glucose known as glycolysis; one molecule of glucose breaks down into two molecules of this

endocytosis

a portion of the plasma membrane invaginates to envelop a substance or fluid; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis

phagocytosis

endocytosis of a solid particle

pinocytosis

fluid uptake by endocytosis

receptor-mediated endocytosis

form of endocytosis that utilizes a membrane protein receptor to concentrate specific molecules of interest

exocytosis

when vesicles within the cell fuse with the plasma membrane during secretion; ex: neurotransmitters, hormones

cytoplasm

contents of a cell between the nucleus and plasma membrane (consists of cytosol and organells)

cytosol

fluid portion of the cytoplasm

organelle

small membranous structure with a specific structure and function; allows for compartmentalization of the cell

cytoskeleton

maintains cells shape, anchors organelles, and is used in cell motility; consists of microtubules, intermediate filaments, and microfilaments

microtubules

long hollow protein cylinders present in cytoplasm, cilia, and flagella
-used as tracks for organelle movement (rollercoaster track analogy)

intermediate filaments

protein fibers that provide support and strength

microfilaments

actin fibers that move organelles and the cell

centriole

short cylinders of microtubules; divides and organizes spindle fibers during mitosis and meiosis

centrosome

a pair of centrioles that functions as microtubule organizing center; active during cell division

nucleus

membranous organelle that houses chromosomal DNA

nuclear envelope

double membrane with nuclear pores that encloses the nucleus

chromatin

diffuse threads containing DNA and protein

nucleolus

region that produces the subunits of ribosomes

nucleoplasm

semifluid medium inside the nucleus

nuclear pores

pores of the nuclear envelope that allow ribosomal subunits to exit nucleus, and proteins to enter nucleus

ribosomes

carries out protein synthesis using mRNA template; consisted of aggregated protein and rRNA; 20 different amino acids

20

How many amino acids are there?

endomembrane system

a series of membrane organelles that function in the processing of materials for the cell and includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles

endoplasmic reticulum (ER)

continuous with the nuclear envelope and consists of a membranous system of saccules and channels; includes a rough and smooth one

rough ER

studded with ribosomes on side of membrane that faces cytoplasm
-proteins are synthesized by ribosomes and enter ER interior
-where initial processing and modification of proteins begins

smooth ER

continuous with rough ER, but has no ribosomes
-synthesizes phospholipids and has other functions

Golgi apparatus

modifies lipids and prteins from the ER; sorts, packages, distributes, and secretes molecules synthesized by the cell (UPS distribution center analogy)

lysosomes

membranous sacs produced by the Golgi apparatus; contain hydrolytic enzymes; can fuse with endocytic vessicle

vessicles

tiny membranous sacs; can transport phospholipids

mitosis

type of cell division in which daughter cells receive the exact chromosomal and genetic makeup of the parent cell; occurs during growth and repair (nuclear division)

cell cycle

repeating sequence of cellular events that consist of interphase, mitosis, and cytokinesis

autosomes

any chromosome oher than the sex chromosomes

sex chromosomes

chromosome that determines the sex of an individual
-females have 2 X chromosomes
-males have one X and one Y chromosome

sex-linked

refers to the allele that occurs on the sex chromosome, but may control a trait that has nothing to do with the sex characteristics of an individual

X-linked

refers to an allele located on the X chromosome

Pedigree

a graphical representation of matings of offspring over multiple generations for a particular genetic trait

meiosis

type of cell divison that occurs as part of sexual reproduction in which daughter cells receive the haploid number of chromosomes in varied combinations

interphase

part of the cell cycle that consists of growth stage 1 (G1), synthetic (S) stage, and growth stage 2 (G2)

G1 stage

stage of interphase in which the cell returns to normal size; resumes its function in body
-doubles its organelles (ribosomes & mitochondria)

S stage

stage of interphase in which a copy is made of all the DNA in the cell (DNA Replication)
-2 chromatids per chromosome

G2 stage

stage of interphase in which the cell experiences an increase in growth and the final preparations are made for cell division

DNA (deoxyribonucleic acid)

genetic material of all organisms
-composed of 2 complementary strands of nucleotides
-has "sugar-phosphate backbone;" sugar is deoxyribose
-DNA is localized in the cell's nucleus and does not leave
-nitrogenous bases make the "rungs" of the DNA ladder (guanine G, cytosine C, adenine A, thymine T)

Double helix

What is the shape of DNA?

guanine, cytosine, adenine, thymine

What are the four nitrogenous bases of DNA?

guanine (G)

Which nitrogenous base pairs with cytosine (C)?

thymine (T)

Which nitrogenous base pairs with adenine (A)?

chromosome

vehicle by which hereditary information is passed to the next generation
-chromatin condensed into a compact structure

chromatid

one of 2 identical copies of DNA making up a duplicated chromosome

centromere

point of attachment for mitotic spindle; where sister chromatids attach

mitotic spindle

microtubule structure that brings about chromosomal movement

DNA Replication

synthesis of a new DNA double helix prior to mitosis and meiosis
-occurs during synthesis (S) stage of interphase
-parental DNA molecule contains old strands hydrogen-bonded by complementary base pairing
-region of replication; parental DNA is unwound and unzipped; new nucleotides are pairing with those in old strands
-replication is complete; each double helix is composed of an old (parental) strand and a new (daughter) strand

46

How many chromosomes do human cells have?

prophase

first phase of mitosis
-nuclear membrane disappears
-chromatin condenses and becomes visible in the cell as chromosomes
-centrioles separate and migrate to opposite ends of the cell
-spindle apparatus is formed
-longest phase of mitosis

metaphase

middle/second phase of mitosis
-chromosomes are lined up on the central (middle) axis of the cell
-as soon as the chromosomes are aligned, anaphase begins

anaphase

third phase of mitosis
-spindle apparatus shortens, pulling the two arms of the chromosome in opposite directions (away from each other)
-it is very quick, but it is here that the doubled genetic material separates into the exact amount of DNA needed for each daughter cell

telophase

fourth and final phase of mitosis
-the chromosomes, now separates into two equal groups, de-condense into chromatin, and the DNA returns to its original thread-like appearance
-nuclear envelopes form around these chromatin groups
-the center of the cell pinches to form a cleavage furrow
-the furrow deepens, eventually separating the cell into separate cells, each with a nucleus containing the same amount of DNA as the parent cell

reductional division

occurs during meiosis I; goes from diploid to haploid

prophase I

first phase of meiosis I
-chromosomes have duplicated
-homologous chromosomes pair during synapsis and crossing-over occurs

metaphase I

second phase of meiosis I
-homologous pairs align independently at the equator
-independent assortment

independent assortment

deals with the random orientation of homologous chromosomes at the metaphase plate
-a pole may receive ether paternal or maternal homologue for each chromosome pair
-occurs during meiosis I