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IB Bio HL > A2.2: Cell Structure > Flashcards

A2.2: Cell Structure Flashcards

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Biology 101 flashcards
1
Q

What are the characteristics of living things?

A

Metabolism
Reproduction

Homeostasis

Growth
Response to stimuli
Excretion
Nutrition

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2
Q

What is metabolism?

A

The enzyme catalyzed reaction occurring in a cell, including cell respiration
-> Sum of all chemical reactions in a cell

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3
Q

What is reproduction?

A

The production of offspring (can be asexual or sexual)
-> allows life to create more life

Sexual reproduction:
Two parents and the fusion of haploid sex cells one from each parent

Asexual production:
Involves 1 parent

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4
Q

What is homeostasis?

A

The ability to maintain and regulate internal conditions within tolerable limits (ex: temp)
-> all living things have mechanisms that keep their internal environment with a certain range despite changes in external environment

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5
Q

What is growth?

A

The permanent increase in size/mass
-> development is the transformation of the organs

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6
Q

What is response to stimuli?

A

Also known as sensitivity:
Ability to respond to external or internal changes in the environment and thus improving chances of survival

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7
Q

What is excretion?

A

The disposal of metabolic waste products, including CO2 from respiration

Humans -> usually through lungs and kidneys
Plant -> usually via leaves, roots and stem
Unicellular -> cell membrane

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8
Q

What is nutrition?

A

Gaining energy and nutrients for growth and development either by absorbing organic matter or by synthesizing organic molecules

Autotrophs -> use external energy to synthesize carbon compounds from simple inorganic substances

Heterotrophs -> use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require

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9
Q

Explain how a paramecium carries out all of the life processes

A

(Use image in notes for reference)

Metabolism - cytoplasm
- most metabolic pathways occur in the cytoplasm

Reproduction - macro and micro nucleus
- nucleus can divide to support cell division via mitosis (asexual)

Homeostasis - contractile vacuole
- fills with water (excess from cytoplasm) and expels though the plasma membrane
- manage water content

Growth - food vacuoles/nutrients
- after consuming/assimilating biomass from food -> get larger until it divides

Response - cilia
- wave action of cilia -> moves cell in response to changes in environment

Excretion - anal pore
- plasma membrane controls entry+exit of substances
- includes expulsion of metabolic waste through anal pore

Nutrition - oral groove and food vacuole
- oral groove: guides food particles into the cell
- food vacuoles: contain organism the cell has consumed -> forms at the end of of oral groove

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10
Q

Explain how chlamydomonas carries out all process of life

A

(Use image in notes for reference)

Metabolism - cytoplasm, mitochondria, chloroplast
- cytoplasm: contains dissolved enzymes that catalyze metabolic reactions
- mitochondria; cellular respiration
- chloroplast: photosynthesis

Reproduction - nucleus
- divides via mitosis (asexual)
- can fuse+divide to carry out a form of sexual reproduction

Homeostasis - contractile vacuole, plasma membrane
- excess water collected then expelled through cell membrane opening

Growth - nucleus, mitochondria, Golgi apparatus
- nucleus: produces protein
- golgi: synthesize protein -> function state
- mitochondria: provides energy (ATP) for growth

Response to stimuli- flagellum; eye spot
- flagellum: allows movement towards light
- eye stoplasma detect light

Excretion - plasma membrane
- oxygen from photo -> diffuses out

Nutrition - chloroplast, pyrenoid
- autotroph -> large single chloroplast to facilitate photosynthesis
- pyrenoid -> concentrate CO2 for increased rate of photosynthesis

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11
Q

What structures do all eukaryotic cells have in common?

A

Nucleus

Free and bound 80s ribosomes

RER+SER

Golgi apparatus

Vesicle

Lysosome

Mitochondria

Cytoskeleton

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12
Q

Differences in eukaryotic cell structure

A

Plastids (double membrane organelles which are responsible for manufacture and storing of food):
Animal: x
Fungi: x
Plant: chloroplast (photosynthesis) and amyloplast (store starch)

Cell wall (external to plasma membrane provides strength and protection + turgor pressure):
X
Composed of chitin + other molecules
Composed of cellulose

Vacuoles (membrane bound organelle, stores/removes water/waste products):
Small and temporary
Large and permanent
Large and permanent

Centrioles (paired cylindrical organelles, 9 x 3 microtubules with radial symmetry):
Used to arrange mitosis spindles during cell division and anchor for cilia and flagella
X (only present in those that have swimming male gamete)
Present in male gametes of moss+fern, absent in conifers and flowering plants

Cilia and flagella (extension of cell surface and help in movement and made of centrioles):
present in many animal cells
X (present in some that have swimming male gamete)
Present in male gamete of moss+fern, absent in conifers and flowering plants

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13
Q

What are examples of eukaryotic cells with atypical structures?

A

Striated muscle fibers/skeletal muscle fibers

Aseptate fungal hyphae

Red blood cells

Phloem sieve tube elements

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14
Q

What are the atypical features of striated muscle fibers/skeletal muscle fibers

A

Longer (up to 300mm in length compared to cardiac muscle cell (100-150 micrometers))

Multiple nuclei surrounded by a single membrane (sarcolemma)
- on edge rather than center
-> allows faster transcription of protein and increase muscle repair/contraction

Formed from multiple cells fused together (reason why many nuclei) that work together as single unit

Challenges the concept that cells work independently of each other even in multicellular organisms

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15
Q

What are the atypical features of aseptate fungal hyphae

A

Hyphae: long thread-like filaments or tubes in fungi
- essential in penetration of food sources, production of digestive enzymes, absorption of release nutrients after digestion
- form mycelium (tangled mess of hyphae)

Coenocytic/aseptate hyphae:
Fungal filaments devoid of septa -> No cross wall (form cellular compartments of fungi)
- rapid nutrient distribution due to rapid cytoplasmic streaming

Nuclei -> multinucleate (several nuclei in one continuous cytoplasmic space)
- from nuclear division followed by no cell division
- metabolic boost/increased metabolism (good because fungus seeks to extract+absorb nutrients form environment)

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16
Q

What are the atypical features of red blood cells

A

Biconcave disc:
Flexible movement (through tiny capillaires)
increased SA for oxygen diffusion and CO2 removal

Haemoglobin:
protein for oxygen binding

Lack of organelles (mitochondria, ER, Golgi, nucleus):
Maximize oxygen transport/haemoglobin/CO2 removal

Acid-base balance:
Through carbonic anhydrase enzyme -> convert CO2 and water to biocarbonates helping balance pH

17
Q

What are the atypical features of phloem sieve tube elements

A

Specialized plant cell
Function: transport/distribution of nutrients

Sieve tube -> thick primary walls (always arranged one above the other)
Phloem parenchyma -> made of parenchyma cells and helps store starch and fat
Phloem fibers -> thick walled, elongate, spindle shaped (dead tissue)

Nucleus of companion cells control activity:
Helps maintain metabolic functions it needs -> will die otherwise
Adjacent to each sieve tube element

No standard organelles:
More open exterior/increased rate of transport

No end cell wall:
Easier transport

18
Q

What is endosymbiosis?

A

Where one organism lives with another as the relationship beneficial

Must have been engulfed by endocytosis

19
Q

How did the nucleus develop?

A

Prokaryote grows -> developed folds in membrane to maintained SA:V ratio

Infolding pinched off -> internal membrane

Nucleotides region enclosed in internal membrane -> nucleus

20
Q

What is the endosymbiotic theory?

A

Theory that chloroplast and mitochondria were once free-living prokaryotes that were engulfed by a larger prokaryote and survived to evolve into the modern organelles we know today

Single common unicellular ancestor for all eukaryotic cells

21
Q

How do scientist think the common eukaryotic unicellular ancestor evolved into heterotrophic cells?

A

Heterotrophs -> cannot prepare their own food and depend upon autotrophs for nutrition

To overcome small SA:V ratio-> ancestral prokaryotes develop folds in membrane

Infoldings -> organelles like nucleus and RER formed

Larger anaerobically respiring cells engulf smaller aerobically respiring prokaryote (not digested)
-> larger cell gain advantage (ready supply of ATP) and gradually cell evolves into heterotrophic eukaryotes with mitochondria

22
Q

How do scientist think the common eukaryotic unicellular ancestor evolved into autotrophic cells?

A

Autotrophs -> organisms that prepare their own food through the process of photosynthesis

Some stage -> heterotrophic cell engulf smaller photosynthetic prokaryote

Cell gain advantage -> alternative source of energy: carbohydrates

Over time -> photosynthetic prokaryote -> chloroplast -> heterotrophs becomes autotrophic eukaryotic

23
Q

How did the mitochondria develop?

A

Aerobic bacterium enters larger anaerobic prokaryote (maybe prey or parasite)

Survives digestion -> valuable endosymbiont (cell which lives in se another cell with mutual benefit)

Aerobic bacterium -> rich source of ATP -> allows cell to out-compete other anaerobic prokaryotes

Host cell grows and divides -> so does aerobic bacterium
-> next generation automatically have aerobic bacterium

Aerobic bacterium evolves and assimilates -> mitochondria

(Chloroplast development would’ve been very similar except the benefit would’ve been cell would use glucose/Starch instead of ATP)

24
Q

What evidence is there supporting the endosymbiotic theory?

A

Double membrane (one original, one from engulfing)
-> inner membrane has proteins similar to prokaryotic cell membrane

Own DNA (naked and circular)

Ribosomes similar to that in prokaryotes (70s)

Roughly same size as bacteria

Susceptible to antibiotic chloramphenicol

Transcribe their DNA and use RNA to synthesize some of their own protein

Can only be produced by division of pre-existing mitochondria/chloroplast

25
Q

What are stem cells?

A

Stem cells are cells that are able to specialize to become different cell types by differentially turning off and on certain genes

26
Q

What is a genome?

A

All the genetic information of an organism

Organisms of the same species share most of their genome
All cells within an organism share the same genome

27
Q

What is differentiation?

A

The development of specialized structures and functions in a cell
Occurs when different cell types express different genes

Can result in differing shapes and presence (or lack thereof) organelles

28
Q

What is gene expression?

A

The process by which the info encoded by a gene is turned into a function

Genes that aren’t housekeeping genes (code for protein that are associated with basic cellular functions) -> differently expressed in different cell types

Regulated by proteins that bind to specific DNA base sequences

29
Q

What are the basic step of protein synthesis?

A

DNA -> transcription (in the nucleus) -> RNA -> translation (RER/Ribosomes) -> folding (Golgi apparatus) -> protein

30
Q

How can environmental conditions change gene expression?

A

Gene expression can be influenced by the external world and internal world

-> external: location or where it develops
Ex: Siamese cats

-> internal: hormones and metabolism
Hormones are molecules that are produced in one cellular location in an organism -> effects another tissues or cell type

31
Q

What are tissues (in a biology context)?

A

A group of cells that have differentiated in the same way to preform the same function

32
Q

What are the benefits of cell specialization?

A

Focus on fewer tasks at once -> increased efficiency/energy conservation

Specialized structures and metabolism

Only do one-few things at a time -> faster evolution

33
Q

What are multicellular organisms?

A

Composed of more than one cell

Specialized cells of the same type come together to form tissue
In multicellular -> cells lose ability to live independently

Exist in:
All animals
All plants
Most but not all fungi and algae

34
Q

What are some examples of multicellular organisms?

A

Epithelial cell -> epithelial tissue -> stomach -> digestive system

Muscle cells -> muscle tissue -> bladder -> urinary system

Neurons (nerve cells) -> nerve tissue -> brain -> central nervous system

Rod and cone cells -> retina -> eyes -> visual system

35
Q

What are the benefits of multicellularity?

A

Multicellularity help cells coordinate and communicate with each other

Helps them thrive in most environments

Allows for organisms to grow and for cell specialization

Being part of a cluster -> survival benefit
- less susceptible to predation

36
Q

What are the two basic steps of multicellular evolution?

A
  1. Formation of cellular clusters from single cells
  2. Differentiation of the cells within the cluster for specialized functions

(Can go back and forth between the two based on what is more beneficial/practical)

37
Q

What are the two hypotheses for how cell clusters may have formed?

A

Groups of independents cells come together

Unicellular organism divides, but daughter cell fails to separate -> group of identical cells

38
Q

P____ and c____

A

Paramecium

Chlamydonas

IB Bio HL (5 decks)

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