Chapter 3 Flashcards
What is a cell?
basic unit of structure and function in the body
What is the function of the plasma membrane?
- surrounds and gives cell form
- selectively permeable
- formed by phospholipid bilayer
What is the function of proteins in the plasma membrane?
- provide structural support
- serve as transporters, enzymes, receptors and identity markers
What is the function of carbohydrates in the plasma membrane?
glycoproteins and glycolipids
- impact negative charge to surface
- can serve as cell surface markers (antigens)
What is bulk transport?
how cells move large molecules and particles across the plasma membrane
- phagocytosis
- endocytosis
- pinocytosis (nonspecific)
- exocytosis to export products
What are cilia for?
movement
What are flagella for?
movement
What are microvilli for?
absorption and membrane transport
- increases surface area
Where are cilia located? What does it look like?
surface of epithelial cells
- hair-like structures that beat in unison
- contains microtubules
What is the cytoplasm?
jellylike matrix
- cytosol + organelles
What is the cytoskeleton?
microfilaments and microtubules in the cytoplasm
- gives cell its shape and structure
What are lysosomes and their function?
vesicle-like organelles containing digestive enzymes
- recycles cell components
- programmed cell death
What is the function of peroxisomes?
detoxification in liver
What is the function of mitochondrias?
energy producers
What are the functions of ribosomes?
protein factories
- 2 rRNA subunits
What is the function of the endoplasmic reticulum?
- synthesis or degradation of molecules
- rough: protein synthesis
- smooth: steroid synthesis and inactivation
What is the function of the golgi complex?
vesicles enter from ER, contents are modified, and then they leaves
- lysosomes and secretory vesicles are formed in the golgi
What is the function of the nucleus?
contains cell’s DNA
- enclosed by nuclear envelope
What do nuclear pore complexes do?
fuse inner and outer membranes together
- small molecules can diffuse through pores
- proteins, RNA are actively transported
What does genome mean?
all genes in an individual or of a species
What is proteome?
all proteins produced by a genome
What is the central dogma of biology?
DNA -> RNA -> Protein
What is transcription?
DNA -> RNA
- occurs in the nucleus and never in the cytoplasm
What is a gene?
sequence of nucleotides that is chemical set of instructions for making a specific protein
What is translation?
RNA -> protein
- occurs in cytoplasm and never in the nucleoplasm
- linear sequence of mRNA determines linear sequence of nucleotides linear sequence of amino acids make up a protein
What are nucleoli?
dark areas in a nucleus containing genes actively making rRNA
What is chromatin?
DNA and its associated proteins (histones)
What are histones?
positively charged and form spools around negatively charged DNA strands
- histone + DNA = nucleosome
What is the function of RNA polymerase?
binds to a “start” sequence on DNA and unzips strands
What are promotor regions for?
regulates levels of transcription
What do transcription factors do?
bind to promoter sequence to initiate transcription
What base pairs are complementary to each other?
G pairs with C
A pairs with U
What 4 types of RNA does transcription produce? What are their functions?
- pre-mRNA: changes in nucleus to form mRNA
- mRNA: contains code for synthesis of a protein
- tRNA: decodes info contained in mRNA
- rRNA: forms part of ribosomes
How does pre-mRNA work?
introns: non-coding regions
Exons: coding regions
- introns are removed and ends of exons spliced together to produce mRNA
How does DNA replication work?
1) Helicase breaks hydrogen bonds to produce 2 free strands of DNA.
2) DNA polymerase binds to each strand and makes new complementary copy of old strand
3) Each copy is composed of 1 new strand and 1 old strand (semiconservative replication)
What phase do most cells exist in?
interphase
What is the cell cycle?
G1 - cell performs normal physiological roles
S - DNA is replicated in preparation for division
G2 - chromatin condenses prior to division
What is mitosis?
cell division
- chromosomes are condensed and duplicated (2 duplicate strands [chromatids] + connection [centromere])
What are the stages of mitosis?
Prophase: chromosomes are visible
Metaphase: chromosomes line up single file along equator by spindle fibers
Anaphase: centromeres split towards opposite poles
Telophase: cytoplasm is divided producing 2 daughter cells
