Lab test 1 Flashcards
Equation to estimate size of specimen:
Field of view / # of cells.
4x - 4.40 mm
10x - 1.75 mm
40x - 0.44 mm
All cells share these four features:
Plasma membrane, cytoplasm, DNA, ribosomes
Two groups of prokaryotic organisms:
Bacteria and archaea
Function of glycocalyx:
Traps water, protects bacterium from desiccation
Layers of general bacterial cell:
Capsule, cell wall, plasma membrane
Slide prep: pipette specimen, apply coverslip (4)
Anabaena, Amoeba, Paramecium, Volvox*
Is Anabaena considered multicellular?
Yes, because the heterocyst is considered a specialized cell.
Anabaena:
Filamentous unbranched chain of cells surrounded by gelatinous sheath.
Heterocyst:
A large, thick-walled cell in the middle of Anabaena; used in nitrogen fixation
Where does cellular respiration occur in cyanobacteria?
Chlorophyll in cell membrane - cyanobacteria are photosynthetic
The human body has over # cell types.
200
Slide prep: wet mount (5)
Elodea, Tradescantia, onion, red pepper, banana*
Cell walls in plants are composed of ___, as opposed to prokaryotic cell walls.
Cellulose
Slide prep for cheek cell:
- Dye.
- Scrape and rub.
- Coverslip.
Microscopy: B/W, white organelles on black background, quite detailed
Phase contrast
Microscopy: glass-like, 3D-like, highly detailed
Differential interference contrast or Nomarski
Microscopy: bright colour on black background, glowing, anemone-like
Fluorescence
Microscopy: two or more colours on black background, very detailed
Confocal laser scanning
Microscopy: B/W, dark organelles on white background, HIGHLY detailed
Transmission electron (TEM)
Microscopy: 3D, weird curves, B/W
Scanning electron (SEM)
Where is the purple pigment of Tradescantia staminal hairs stored? What is it called?
Central vacuole. Anthocyanin.
How much of the cell is occupied by the central vacuole?
85-90%
Function of the vacuole:
Structural support, storage of water/enzymes/ions/proteins/toxins
What are the particles that travel through cytoplasmic strands?
Cellular granules - may be mitochondria
Slide prep for onion epidermal cells:
- Drop of water
- Peel skin from concave surface of onion scale
- Coverslip
Three main types of plastids:
Chloroplasts, chromoplasts, leucoplasts
Chloroplasts:
Site of photosynthesis. Green due to chlorophyll in the thylakoid membranes.
Chromoplasts:
Contain pigment called carotenoids (yellow, orange, red, dark purple). Attracts animals for pollination/seed dispersal.
Slide prep for red pepper:
- Drop of water
- Peel skin from outside of pepper
- Coverslip
Plasmodesmata:
Cytoplasmic connections that run through perforations in the cell wall for communication between cells.
Leucoplasts:
Non-pigmented plastids that store starch/proteins/lipids.
Slide prep for banana (Musa):
Wet mount, then squish
Why do starch grains appear layered?
Each layer corresponds to a day of starch deposition
What is responsible for formation of pseudopodium?
Microfilaments in the cytoskeleton, composed of actin subunits
Function and shape of contractile vacuole:
Osmoregulation, perfectly circular
What passes through nuclear pores?
RNA
Why do mitochondria have finger-like cristae?
To increase surface area available for ATP synthesis
What kinds of cells have cell walls?
Plants/bacteria/archaea/fungi/some protists
Function of the cytoplasm:
Environment for cellular processes
Function of microtubules:
Structure and movement of cilia/flagella, cell organization/shape
Function of microfilaments:
Cell strength, shape, movement
Function of golgi:
Modifies/stores/ships products of ER
Function of lysosomes:
Contains enzymes that digest food/waste
Function of nucleolus:
Ribosome subunit assembly
Function of nucleus:
Determines cell function through control of proteins
Function of ribosomes:
Site of protein synthesis, composed of rRNA and proteins
Function of rough ER:
Initial synthesis and sorting of proteins for export
Function of smooth ER:
Lipid synthesis/modification, detox of drugs/alc, calcium ion storage, glycogen breakdown
What is diffusion?
The random movement of molecules from high to low concentration.
What is osmosis?
Movement of solvent through a selectively permeable membrane from low to high solute concentration
What prevents plant cells from bursting in hypotonic solutions?
Turgor pressure (reaching turgid) - cell wall stops water from entering after a certain amount
Plasmolysis:
Reduction of turgor pressure (water leaves cell) - vacuole decreases and plasma membrane pulls away from cell wall
Binary fission in prokaryotic cells:
Single chromosome in the form of a circular loop of DNA duplicates then separate
Aside from DNA, what else is duplicated when a cell undergoes binary fission?
Plasmids
Functions of mitosis:
Production and maintenance of multicellularity (zygote to embryo to adult)
Asexual reproduction
Replacement of old/dead tissues
When do chromosomes condense? uncoil?
Prophase; telophase
What is a blastodisc?
Fertilized egg in multicellular embryonic stage
Colony:
Individual cells/organisms that stick together (gelatinous matrix) and may communicate - NO SPECIALIZED CELLS
What is the function of the eyespot in algae?
Orients alga towards light
What is the function of the pyrenoid in algae?
Responsible for synthesis of starch and photosynthetic sugars
How do cells of a colony communicate?
Cytoplasmic bridges - necessary for coordination of flagellar movement.
What is the difference between Gonium and Eudorina colonies?
Gonium is flat, Eudorina is spherical
Slide prep for Volvox:
- Pipette a drop
- Observe on 10x WITHOUT coverslip
- Coverslip, 40x
Two types of Volvox cells:
Somatic, reproductive.
How does Volvox reproduce?
Specialized cells undergo repeated cell division. When mature, the parent organism rupture and releases small spherical daughter organisms.
What human cells are haploid?
ONLY sex cells
How to tell whether cells are diploid/haploid? duplicated or not?
If it has a twin, it is diploid. If it has attached sister chromatids, it is duplicated.
Homologous chromosomes:
Twin chromosomes (can be duplicated or not)
Genotype:
Ordered list of alleles carried by a gene
Allele:
Particular form of a gene
What is a bivalent?
Homologous chromosomes hanging out together
What important, unique things happen in Prophase I of meiosis?
Formation of bivalents, crossing over
Slide prep for chive flower bud:
- Two medium-sized buds
- Two drops of stain
- CHOP!
- Drag clumps aside
- Coverslip
Haploid generation of plant life cycle:
Gametophyte. Produces gametes.
Diploid generation of plant life cycle:
Sporophyte. Produces spores.
Site of meiosis in sporophytes:
Sporangia
Sorus (pl. sori):
Brown spots that develop under mature fern leaves
Rhizome:
Horizontal underground stem of fern - bears roots
___ undergo meiosis to form spores.
Sporocytes
During which parts of the plant life cycle is it haploid?
Between spore formation to fertilization of archegonium
Prothallus:
Fern gametophyte - heart-shaped plant that develops fine, root-like rhizoids