Module 2 Exam Intro to Biology

gene expression in eukaryotes

- Transcription occurs in the nucleus - RNA is processed - RNA is moved to the cytoplasm - Translation occurs in the cytoplasm

mRNA translation

-cytoplasm has proteins that determine whether translation takes place -environmental conditions can delay translation (ex: red blood cells cannot produce hemoglobin unless heme is available) -the longer mRNA remains in the cytoplasm before it is broken down, the more gene product is produced (can be affected by length of ply A tail or presence of hormones)

gene expression in prokaryotes

-no nucleus -transcription and translation are coupled

3 phases of translation

1. Initiation 2. Elongation 3. Termination

Microtubules

13 long chains of tubulin dimers (2 linked tubulin molecules) that can change in length by removing dimers. (controlled by centrosomes, microtubule organizing center, near nucleus)

actin filaments

2 globular chains actin monomers to form a long filament-- supports cell by forming a web under the plasma membrane

What do nucleotides consist of?

5 carbon sugar, phosphate group, nitrogenous base

External signals

> growth factors and hormones > stimulate cells to go through the cell cycle

p53 tumor suppressor gene

> produces a protein that checks the DNA for damage before it proceeds through the G1 checkpoint > if there are breaks in the DNA, the cell is instructed to enter into G0 phase > if these repairs cannot be repaired, the cell undergoes apoptosis

Chargaff's Rule

A=T and C=G

Telomerase

An enzyme that catalyzes the lengthening of telomeres. The enzyme includes a molecule of RNA that serves as a template for new telomere segments.

Bacterial structure

Cytoplasm surrounded by plasma membrane and cell wall, capsule, enzymes, nucleoid, ribosomes, flagella

Central Dogma of Molecular Biology

DNA -> RNA -> Protein

cell recognition proteins

Enable our body to distinguish between our own cells and cells of other organisms-without it pathogens would invade

Watson and Crick

Figured out structure of DNA was a double helix

What are the three checkpoints in a cell cycle?

G1 checkpoint, M checkpoint, checkpoint,

three phases of interphase

G1, S, G2

Heterchromatin

Highly compacted chromatin that is not accessible for transcription (inactive) ex barr body

Mitochondria

Powerhouse of the cell-- can form long moving chains or remain in one location (where energy isnt needed) -bound by a double membrane.

What happens during interphase?

The cell grows, copies its DNA, and prepares for cell division.

Rosalind franklin

Woman who generated x-ray images of DNA

housekeeping genes

active genes that govern functions that are common to many types of cells including glucose metabolism

mRNA processing

after transcription, removal of introns and splicing of exons occur before mature mRNA leaves nucleus and passes into the cytoplasm. (ex fruit fly gene)

senescence

aging of cells

channel proteins

allow one/few types of specific molecules to move readily through the membrane (Ex: aquaporins- allow water to enter or exit a cell)

Motor proteins:

allows cells and organelles to move

Ex of what to view through an electron microscope:

amino acid

cellular reproduction

an original cell divides and produces two identical daughter cells (growing, tissue repair, single celled orgs reproduce etc

Ex of what you can view through an electron OR light microscope:

animal cell, chloroplast, plant cell

Junction proteins

assist cells in cell adhesion and communication

smooth ER

attached to rough er, no ribosomes, synthesizes lipids (phospholipids, steroids)- forms transport to the golgi apparatus

DNA replication in eukaryotes:

begins at specific sites on a double helix (called origins of replication) and proceeds in both directions -- replication bubble is where the process of replication occurs -- proceeds until double helix is copied

Transcription process:

begins when RNA polymerase binds to a promoter -- rna polymerase opens DNA helix so complementary base pairing cna occur-- polymerase adds new rns nucleotides complementary to those in the templates dna strand-- resulting mRNA transcript is a copy of sequence of bases in template dna strang, mRNA is ready to be processed

M checkpoint

between metaphase and anaphase to ensure proper attachment of chromosomes and will be distributed to the daughter cells (cycle wont continue until ever chromosome is ready for nuclear division)

M phase

both division of the nucleus and the cytoplasm

cellular respiration

breakdown of carbohydrates involving the cytoplasm-- oxygen needed, carbon dioxide is given off

Initiation

brings all translation components together (subunit attaches, anticodon pairs with tRNA, large subunit joins the small)

Motile

can travel through blood and lymphatic vessels to other parts of the body -- leads to metastasis

G1 phase

cell doubles organelles (mito and ribo), accumulates materials used for DNA replication-- integrates internal and external signals and decides whether to continue the cell cycle

Apoptosis

cell rounds, nucleus collapses, chromatin condense, dna fragments, plasma mebrane blisters forming blebs, cell fragments

cytokinesis in plants

cell wall doesnt permit cytokinesis by furrowing--involves the building of new plasma membranes and cell walls between daughter cells

Plasma membrane

cells outer membrane which acts as the boundary between the inside and outside of a cell.

Why are cells so small?

cells rapidly exchange materials with the external environment--needs surface area large enough to allow efficient movements of nutrients into the cell and waste materials out

m phase

centrosomes separate and move to opposite sides of the nucleus where poles of spindles are formed-- nuclear envelope breaks down and spindle fibers take over center of cell (spindle equator)

growth factor

chemical signal activates cell signaling pathways bu bringing phosphorylation of signaling proteins

Endosymbiosis

chloroplasts derived from photosynthetic bacteria enter a eukaryotic cell

Metaphase

chromosomes align at the spindle equator

prophase

chromosomes condense, each consists of 2 chromatids held at centromere-- nucleolus disappears and nuclear envelope is broken down

cytokinesis in animals

cleavage furrow constricts like a drawstring to separate the cells

gap junction

communication, 2 identical plasma membrane channels join

Organelles

compartments of a eukaryotic cell-carry out specialized functions that together allow the cell to be more efficient and successful

G2 phase

completion of the DNA replication to the onset of mitosis-- cell synthesizes proteins needed fir division (microtubule protein) important in division

chromosomes

condensed, coiled chromatin with rod like structures

chromosome

consists of DNA complexed with proteins, transmits genetic info from previous generation to the next

Exons

contain protein-coding regions of the gene

Carcinogenesis

development of cancer

Angiogenesis

development of new blood vessels

Cytokinesis

division of the cytoplasm

Mitosis

division of the nucleus

When does cytokinesis begin?

during telophase and continues after nucelei formed in daughter cells--cycle complete

S phase

each chromosome has 1 chromatid consisting of single dna doible helix, each chromose has 2 sister chromatids (1 double helix), remains attached to the centromere-- dna replication produces duplicate chromosomes

codon

each sequence of three bases standing for one of the 20 possible amino acids. *can help protect against possibly harmful mutations that might change sequence of AA*

Proteosomes

enzyme complex that destroys proteins when they are no longer needed

Kinases

enzymes remove phosphate from ATP and add it to different molecules (on and off switch for cellular activities)-- active in the removal of nuclear membrane and condensation of chromosomes in early prophase.

contact inhibition

eukaryotic cells stop diving preventing cells from overgrowing

inborn errors of metabolism

family members have same metabolic disorder due to lack of functional enzyme in a metabolic pathway

Chromatin

fibrils consist of dna and proteins, eukaryotic cell isnt undergoing cell division, wound around core of 8 protein molecules (histones) network of dna, rna and protein found in the nucleoplasm

Cristae

folds in the inner membrane of mitochondria to increase surface area

angiogenesis

formation of new blood vessels

oncogenes

forms when proctooncogenes mutate and become cancer causing genes

Ex of what to view through a light miscroscope:

frog egg

What do proteins determine?

function

The protein ras

functions in signal transduction pathways that lead to transcription of many genes -- normally inactive but reception of a growth factor leads to activation (cancer can occur due to repeated cell division)

Cell

fundamental unit of life, diverse in shape and function

Introns

genes in humans interrupted by segments of DNA not coding for protein (intervening segments)

Operon

group of structural and regulating genes functioning as a single unit

what are the 2 processes of cellular reproduction?

growth- cell duplicates contents including including organelles and dna cell division- dna and other cellular contents of parent cell distributed to the daughter cell.

G2 checkpoint

halts until DNA replication verified-- prevents initiation of m phase

eukaryotic cells

has nucleus that houses their dna

Receptor proteins

has shape that allows signal molecule to bind to it (causes protein to change shape and bring on a cellular response)

sister chromatids

held together at the centromere, contains identical double helix

Process of DNA replication:

helix separates and unwinds by breaking hydrogen bonds between nucleotides and unwinding helix using the enzyme helicase-- new nucleotides added to parental template strand-- nucleotides ever present in the nucleus will complementary base pair to a single stranded parental strang--- addition of new strand completed using DNA polymerase-- daughter strand is synthesized by DNA polymerase in a 5'-3' direction-- any breaks sealed by DNA ligase

endomembrane system

helps compartmentalize the cell so enzymatic reactions are restricted, increasing efficiency-- nuclear envelope, ER membranes, golgi apparatus, and vesicles

Surface are to volume ratio

higher ratio of surface area to internal volume, faster the exchange of materials within an environment.

Plasmodesmata

how living cells in plants are connected, membrane lines channels passing through the cell wall (water and small molecules)

G1 checkpoint

if cell cycle passes this checkpoint it can divide, can enter G0 if it doesnt divide. Apoptosis can occur if DNA damaged beyonf repair

Centrioles

in centrosome, organelles composed of microtubules

DNA Transcription factors:

in eukaryotes, is the DNA binding proteins that help RNA polymerase bind to a promoter

alt mRNA splicing

increases number of protein products that can be made from a single gene (passes from cell nucleus into cytoplasm for translation after processed)

tumor suppressor genes

inhibit the cell cycle and promote apoptosis

Stroma

inner space

adhesion junction

intercellular cytoplasm plaques attach to cytoskeleton and joined by intercellular filaments (sturdy but flexible)

Cytoskeleton

interconnected protein filaments and tubules extending from the nucleus to the plasma membrane in eukaryotic cells. (microtubules, intermediate filaments, active filaments)

How are checkpoints controlled?

internal and external signals (molecules that stimulate or inhibit cell function)

Thykaloid space

internal compartment formed by lumens of thykaloid sacs

Cyclins

internal signaling proteins that increase and decrease as the cell cycle continues

chromatin condensation

keeps genes turned on or off, more tightly chromatin is compacted less often genes within it are exposed

prokaryotic cell

lack membrane bound nucleus, dna is located in the nucleoid (bacteria-first cells on earth)

Characteristics of cancer:

lack of differentia, abnormal nuclei, dont undergo apoptosis, form tumors, undergo metastasis and promote angiogenesis

how is lac operon turned on?

lactose binds to repressor and changes shape which makes it unable to bind to operator, RNA polymerase binds to promoter.

Translation process:

leads to protein synthesis, requires several enzyme mRNA, tRNA, and rRNA -- tRNA takes AA to ribosomes, AA binds to one end of the molecule, opposite end contains anticodon, group of three bases complementary to specific codon of mRNA-- order of codons in mRNA determine order of tRNAs and bind at ribosomes-- when complete, protein contains sequence of AA originally specified by DNA

euchromatin

less compact form of chromatin containing active genes (forms when heterchromatin undergoes unpacking)

Nuclear pore

located in the nuclear envelope that allows nucleus to communicate with the cytoplasm

Regulatory gene

located outside of the operon and codes for a repressor (protein that binds to the operator which is next to the promoter)

Capsid

made of protein and inner core DNA-- results show viral dna enters bacteria causing formation of new viruses.

Vacuoles

membranous sacs larger and more specialized than vesicles

Vesicles

membranous sacs that enclose molecules and keep them separate from cytoplasm-move around the cytoskeleton which maintains cell shape and assists with cell movement

Which two organelles are responsible for generating the majority of energy needed to perform cellular processes?

mitochondra and chloroplast

Thykaloids

mix of enzymes and disclike sacs

cillia

move stiffly, short, projection from plasma membrane

major motor proteins

myosin, kinesin, dynein (myosin interacts with actin filaments when movement occurs, kinesin and dyenin move along the microtubules)

Cell plate

newly formed plasma membrane expanding outward reaching old plasma membrane and fuses--- new releases molecules that form new plant cell walls

mRNA processed:

newly synthesized primary mRNA must be processed to be used properly (capping, addition of poly A tail, splicing) --- after processing=matire mRNA molecule

Animal cells

no cell wall, extracellular matrix (fibrous proteins and polysaccharides) collagen and elastin

Where is ribosomal RNA produced?

nucleolus

Cell signaling

occurs because a chemical signal binds to a receptor protein in a target cell's plasma membrane

Cell cycle

orderly sequence of stages take place between time new cells arisen from division of a parent to point of rise of two daughter cells

Golgi apparatus

organelle consisting of sacs and vesicles that processes, packages, and distributes molecules about or from the cell

DNA

organized into genes and has a specific sequence of nucleotides

Translocations

part of one chromosome breaks off and attaches to another -- can lead to cancer

Enzymatic proteins

participate in metabolic reactions

transport proteins

passage of molecules and ions through the membrane-combine with substance with input energy for help (Ex; sodium and potassium ions across the nerve cell membrane-nerve conduction)

Interphase

period of the cell cycle between cell divisions, cell performs usual functions

Plasma membrane structure:

phospholipid bilayer with embedded proteins, outer layer- phospho heads face towards ext environment, inner layer- phospho heads face interior of cytoplasm

tight junctions

plasma membrane proteins attach to eachother

3 characteristics of cells:

plasma membrane, cytoplasm, dna

Elongation

polypeptide increases in length one amino acid at a time

Transcription

portion of DNA serves as a template for mRNA formation

Plant structure

primary cell wall contains cellulose fibrils and non-cellulose substances allowing the wall to stretch. (adhesive substances outside the wall holds two plant cells together) Secondary cell wall used for added strength and has more cellulose fibrils and lignin-common ingredient

Centrosome

primary microtubule organizing cell center - two barrel like structures in an animal cell, centrioles and microtubules (plants have centrosomes but lack centrioles)

tRNA

produced in nucleus in eukaryotes, transfers amino acids in cytoplasm to the ribosomes, 20 different AA (each has its own tRNA molecule) Translation joins the AA to form a polypeptide chain.

mRNA

produced in nucleus of eukaryotic cell and in the nucleoid of prokaryotic cell, transcription- DNA serves as a template for formation -- once formed, mRNA carries genetic info form DNA in the nucleus of ribosomes in the cytoplasm where protein synthesis occurs

rRNA

produced in the nucleolus in eukaryotic cells, portion of DNA serves as a template for formation, rRNA joins with proteins made in cytoplasm to form ribosomes -- each subunit has its own proteins and rRNA-- subunits leave the nucleus and join in the cytoplasm when protein synthesis is about to begin-- proteins are synthesized at the ribosomes.

Microvilli

projections that increase the cell's surface area

Why are telomeres important in regulating cell division?

promote chromosomal stability so replication can occur

Procto-oncogenes

promote the cell cycle and inhibit apoptosis

4 phases of mitosis in order:

prophase, metaphase, anaphase, telophase

fluid mosaic model

protein embedded in membrane and have pattern within a fluid bilayer

Histone

protein molecule around which DNA is tightly coiled in chromatin-- looks like beads on a string

What does the DNA sequence of bases determine?

proteins in a call

Cell wall

provides support, found in plants, fungi, and protists

splicing

removal of introns, joining of exons

how is lac operon turned off?

repressor attaches to operator, transcription unable to take place due to RNA polymerase unable to bind to promoter

Philadelphia chromosome

result of translocation between chromosomes 9 and 22

intermediate filaments

run between the nuclear envelope and plasma membrane

Translation

sequence of mRNA bases determines sequence of amino acids in a polypeptide

Glycoproteins

short chain sugars attached to protein (helps protein perform function ; identity of cell)

RNA structure and function:

single-stranded, found in nucleus and cytoplasm, dna assistant, ribose suagr, AUCG, mRNA translated to make proteins, rna allows protein synthesis to occur according to the genetic info dna provides.

anaphase

sister chromatids separate become daughter chromosomes

2 ribosomal subunits

small, large -- subunits leave the nucleus and join in the cytoplasm to form ribosomes as protein synthesis begins

flagella

snakelike, long, used for locomotion

sexual reproduction

sperm and egg produces offspring different from parents

binary fission

splitting of a cell into two new cells, asexual reproduction because it produces two cells identical to the orginal

Granum

stack of thylakoids

Centrosome duplication

starts at s phase and complete by g3

Termination

stop codon appears at A site, polypeptide and assembled components that carried out protein synthesis separate--- release factor binds to stop codon and cleaves polypeptide from last tRNA

Nucleus

stores genetic information

Spindle

structure of the cytoskeleton to pull chromatids apart (has fibers made of microtubules able to assemble and disassemble)

Rough ER

studded with ribosomes on the side of the membrane facing the cytoplasm allowing it to synthesize polypeptides.

Endoplasmic Reticulum (ER)

system of membranous channels continuous with the outer membrane of the nuclear envelope

epigenetic inheritance

the inheritance of changes in gene expression that are not the result of changes in the sequence of nucleotides on the chromosome (ex calico cat)

DNA replication

the process of making a copy of DNA: dna/proteins packaged into a set of chromosomes which allows dna to be distributed to the daughter cells (due to proteins and enzymes in the nucleus)

Telophase and Cytokinesis

the spindle disappears as new nuclear envelopes form around the daughter chromosomes. Each nucleus contains the same number and kinds of chromosomes as the original parent cell. Remnants of spindle fibers are still visible between the two nuclei. Division of the cytoplasm begins.

3 types of junctions

tight junctions, adhesion junctionw, gap junctions

Two processes of gene expression

transcription and translation

Ribosomes

use genetic information to manufacture proteins needed for cellular structure and metabolic activities.

Chloroplast

use solar energy to synthesize carbohydrates, bound by a double membrane (outer and inner)

gene expression

using information within a gene to synthesize a protein

What are the four characteristics of dna structure?

variability, ability to replicate, storage of info, ability to change or mutate

Lysosomes

vesicles produced by golgi apparatus that digest molecules coming into a cell and breakdown damaged organelles

How does euchromatin become active?

when histones no longer bar access to DNA -- only possible for a gene to be turned on and expressed in a eukaryotic cell

Lumen

where proteins take shape