BIOLOGY FINAL VOCAB

microfilament

thin actin filaments that support cell shape and help with cell movement and division

intermediate filament

rope-like protein fibers that provide structural stability and anchor organelles

microtubule

hollow tubes made of tubulin that support the cell, aid in transport, and form spindle fibers

cilia

short, hair-like projections that move fluid or materials across the cell surface

flagella

long, whip-like structures that enable a cell to move, usually one or a few per cell

cell membrane

a selectively permeable phospholipid bilayer that controls what enters and exits the cell

concentration

the amount of solute dissolved in a given volume of solvent

concentration gradient

the difference in solute concentration between two areas

equilibrium

the state when the concentration of substances is equal throughout a space

carrier protein

a membrane protein that changes shape to move specific substances across the membrane

selectively permeable

allowing some substances to cross a membrane while blocking others

solute

the substance that is dissolved in a solution

solvent

the substance that does the dissolving in a solution, usually water in biological systems

hypertonic

a solution with a higher solute concentration compared to another solution, causing cells to lose water

hypotonic

a solution with a lower solute concentration compared to another, causing cells to gain water

isotonic

a solution with equal solute concentration compared to another, causing no net water movement

plasmolysis

the shrinking of a plant cell's cytoplasm due to water loss in a hypertonic solution

types of junctions

tight junctions seal cells to prevent leakage

gap junctions allow direct communication via channels

desmosomes anchor cells together for strength

role of the cell membrane

controls what enters and exits the cell by being selectively permeable

maintains homeostasis and supports communication and transport

active transport

movement of substances against the concentration gradient using energy (ATP)

passive transport

movement of substances down the concentration gradient without energy

diffusion

passive movement of molecules from high to low concentration

facilitated diffusion

passive transport using proteins to help molecules cross membranes

osmosis

diffusion of water across a selectively permeable membrane

endocytosis

active transport where the cell engulfs materials in vesicles

exocytosis

active transport where vesicles fuse with membrane to release substances

pinocytosis

type of endocytosis where cells engulf fluids ("cell drinking")

phagocytosis

type of endocytosis where cells engulf large particles ("cell eating")

hypertonic solution

higher solute concentration than inside the cell causing water to leave the cell

hypotonic solution

lower solute concentration than inside the cell causing water to enter the cell

isotonic solution

equal solute concentration causing no net water movement

cytolysis

bursting of a cell due to excess water intake in a hypotonic solution.

nucleotide

the basic building block of nucleic acids made of a sugar, phosphate, and nitrogen base

deoxyribose

a five-carbon sugar found in dna nucleotides

nitrogen base

a molecule in nucleotides that forms the genetic code (adenine, guanine, thymine, cytosine, uracil)

adenine

a purine nitrogen base that pairs with thymine in dna and uracil in rna

guanine

a purine nitrogen base that pairs with cytosine

thymine

a pyrimidine nitrogen base in dna that pairs with adenine

cytosine

a pyrimidine nitrogen base that pairs with guanine

uracil

a pyrimidine nitrogen base in rna that replaces thymine and pairs with adenine

double helix

the twisted ladder structure of dna with two strands

single helix

the structure of rna with one strand

replication

the process of copying dna before cell division

nucleus

the cell organelle where dna is stored and replication and transcription occur

cytoplasm

the cell fluid outside the nucleus where translation occurs

transcription

the process of copying a dna sequence into mrna

codon

a sequence of three mrna bases that codes for an amino acid

anticodon

a sequence of three trna bases complementary to an mrna codon

translation

the process of assembling a protein at the ribosome using mrna and trna

amino acid

the building block of proteins coded for by codons

mrna

messenger rna that carries genetic info from dna to ribosomes

trna

transfer rna that brings amino acids to the ribosome during translation

rrna

ribosomal rna that makes up the ribosome's structure

protein

a chain of amino acids folded into a functional molecule

hydrogen bonds

weak bonds between complementary nitrogen bases holding the dna strands together.

cell cycle

the series of stages a cell goes through to grow and divide

chromatin

loosely packed dna and proteins found in the nucleus during interphase

chromosome

tightly coiled dna structure visible during cell division

chromatid

one of two identical halves of a duplicated chromosome

interphase

the cell cycle phase where the cell grows and dna is replicated

g1

first gap phase of interphase where the cell grows and carries out normal functions

s

synthesis phase of interphase where dna is replicated

g2

second gap phase of interphase where the cell prepares for mitosis

prophase

mitosis phase where chromatin condenses into chromosomes and spindle fibers form

metaphase

mitosis phase where chromosomes line up in the cell's center

anaphase

mitosis phase where sister chromatids are pulled apart to opposite poles

telophase

mitosis phase where chromosomes reach poles and nuclear membranes reform

cytokinesis

the process where the cytoplasm divides, forming two daughter cells

spindle fiber

protein structures that move chromosomes during mitosis

centromere

the region where sister chromatids are attached.

autosome

any chromosome that is not a sex chromosome

cell cycle

the sequence of growth and division phases a cell undergoes

chromatin

loosely packed dna and proteins in the nucleus during interphase

chromosome

tightly coiled dna structure visible during cell division

chromatid

one half of a duplicated chromosome

crossing over

exchange of genetic material between homologous chromosomes during meiosis

diploid

a cell containing two complete sets of chromosomes (2n)

haploid

a cell containing one set of chromosomes (n)

interphase

cell cycle phase when the cell grows and duplicates dna

prophase

first phase of mitosis or meiosis when chromosomes condense and spindle fibers form

metaphase

phase where chromosomes align in the cell center

anaphase

phase where sister chromatids separate to opposite poles

telophase

phase when chromosomes reach poles and nuclear envelopes reform

cytokinesis

division of the cytoplasm forming two daughter cells

spindle fiber

microtubules that move chromosomes during cell division

centromere

region where sister chromatids attach

oocyte

immature female gamete cell

oogenesis

process of egg cell (ovum) formation in females

spermatocyte

male germ cell that undergoes meiosis to form sperm

spermatogenesis

process of sperm cell formation

fertilization

fusion of male and female gametes to form a zygote

mutations

changes in the dna sequence that can affect genetic information

transgenic

an organism that contains genes from another species

splicing

process where introns are removed from rna and exons joined to form mature mrna

inbreeding

mating of closely related individuals to maintain desired traits

selective breeding

choosing parents with specific traits to produce offspring with those traits

cloning

producing genetically identical organisms from a single cell