1 — cells Flashcards

1
Q

How single cells eventually form a system

A

Similar Cells -> different tissues working tgt to carry out a specific function -> organ -> system

E.g. muscle cells -> muscular tissues work with nervous & gland tissues to digest food -> forms organ: stomach

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2
Q

Light vs electron micrograph

A
  • Light micrograph: coloured images
  • Electron micrograph: black-and-white images, can be artificially coloured
    Higher range of magnification
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3
Q

Characteristics of cell membrane

A
  • Partially permeable
  • Controls movement of substances entering/leaving the cell
  • Filters by size
  • Made up of lipids&proteins
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4
Q

Characteristics of Cytoplasm

A
  • Site for chemical activities in cell to occur
  • Contains specialised structures that perform a specific job within the cell: organelles
    • Endoplasmic reticulum
    • Golgi body
    • Ribosomes
    • Mitochondria
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5
Q

Characteristics of nucleus

A
  • Surrounded by nuclear membrane
    • Separates nucleus contents from the rest of cytoplasm
  • May contain >/1 nucleoli & chromatin, which contains DNA
  • Part of cytoplasm & protoplasm
  • Controls cell activities, essential for cell division
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6
Q

Characteristics of cell wall

A
  • Made of cellulose
  • Protects cell from injury
  • Gives the cell a fixed shape
  • Fully permeable
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7
Q

Characteristics of chromatin

A
  • Made up of proteins and DNA (deoxyribonucleic acid)
    • stores hereditary info
    • Carries instructions that a cell needs for carrying out its activities
    • condense and shortens to become chromosomes
      • Only present during mitosis (cell division)
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8
Q

Endoplasmic reticulum (smooth vs rough comparison)

A

Appearance:
RER: Appears rough cus of ribosomes attached to membrane
SER: Appears smooth cus absence of ribosomes attached to membrane

Shape:
RER: A network of flattened spaces lined with a membrane (filled with fluid)
SER: More tubular than RER

Connections:
RER: Continuous with nucleus membrane
SER: Continuous with RER

Functions:
RER: Transport proteins made by ribosomes to Golgi Apparatus for excretion out of cell
SER: - Synthesise fats & steroids (sex hormones in mammals)
- Carries out detoxification: Converts harmful substances -> harmless substances

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9
Q

Ribosomes

A

Sites to synthesise proteins
- Attached to RER membrane
- Proteins made transported out of cell (usually)
- Lie freely in cytoplasm
- Proteins made used within cell

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10
Q

Golgi Body/Apparatus (GB/A)

A
  • Consists of stack of flattened spaces surrounded by membranes
  • Chemically modifies, stores & packages substances made by ER in vesicles for secretion out of cell
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11
Q

Vesicles

A
  • Transport substances within cell
  • Contains substances made by ER, pinched off from ER -> fuse with GB, release contents into GB to be modified-> secretory vesicles (becomes secretory now) containing modified substances pinched off from GB -> move to cell membrane -> fuse with cell membrane -> contents released out of cell
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12
Q

Mitochondria

A
  • Singular: mitochondrion
  • Site for aerobic respiration where glucose is oxidised to release energy for cellular activities (such as)
    • Growth
    • Reproduction
  • Glucose + oxygen -> CO2 + H2O + large amt of energy
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13
Q

Chloroplasts

A

Contains a green pigment chlorophyll required for photosynthesis to occur

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14
Q

Vacuoles

A
  • A fluid-filled space enclosed by a partially permeable membrane
  • Store substances within a cell
  • Plant: large & central; contains cell sap
    • Contains dissolved substances like sugars
    • Mineral salts
    • & amino acids
  • Animal: many & small; contain water & food substances; usually exists temporarily
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15
Q

Differences betw plant cell n animal cells

A

Presence of cell wall:
PC: P (present)
AC: A (absent)

Vacuoles:
PC: Large, central, contains cell sap
AC: Many, small, contains water & food substances

Presence of chloroplasts
PC: P
AC: A

Presence of centrioles:
PC: A
AC: P

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16
Q

Similarities betw a typical plant cell n an animal cell

A

Both has presence of protoplasm and presence of RER+SER

17
Q

Movement of proteins in cells

A
  • Proteins made / synthesised by the ribosomes on the rough endoplasmic reticulum (RER) enter into RER. [1]
  • The manufactured proteins are transported in vesicles that are pinched off from the RER and are transported to the Golgi apparatus. [1]
  • The Golgi apparatus stores and chemically modifies the proteins made by RER and packages them into vesicles. [1]
  • The secretory vesicles containing the modified proteins are pinched off from the Golgi apparatus. The vesicles then move to the cell membrane and fuse with the membrane. This releases the contents in the vesicles into the outside of the cell. [1]
18
Q

Differentiation Definition

A

Process by which a cell becomes specialised for a specific function

19
Q

RBCs characteristics

A
  • Contains haemoglobin (red pigment) that binds to oxygen & transports it around body
  • Has circular, biconcave shape -> ^ surface area-to-volume ratio -> oxygen can diffuse in & out faster
  • Lacks nucleus -> more space -> Store more haemoglobin for transport of O2
  • Flexible -> squeeze thru capillaries easily
20
Q

Muscle cell characteristics

A
  • Elongated, cylindrical in shape
  • Contains many nuclei + mitochondria to release energy for contraction of muscle cell
  • ^ mitochondria -> ^ aerobic respiration -> faster release of energy for contraction of muscle cells
21
Q

Root hair cell

A

Long & narrow root hair -> ^ surface-area-to-volume ratio -> absorbs water + dissolved mineral salts faster

22
Q

Compare the structures of a RBC&RHC in carrying out their functions efficiently

A
  • Similarity: increases SA:V for faster rate of diffusion of substances
  • Differences: RBC no nucleus, RHC got nucleus; RBC got haemoglobin, RHC no; RHC got many mitochondria, RBC not a lot of mitochondria
23
Q

Compare and contrast the similarities and differences between plant cells and animal cells. [6]

A

Similarities:
Both have nucleus [1]
Both have cell membrane / mitochondria/ RER/ SER [1]

Differences:
Plant cell have cell wall but animal do not have [1]
Plant cell have chloroplast but animal do not have [1]
Plant cell have a large central vacuole but animal cells have small and numerous vacuoles [1]

24
Q

Identify a named organelle that can only be seen under electron
microscope and state its functions. [2]

A

Golgi apparatus [1]:
stores, chemically modifies and packages manufactured proteins in
vesicles for secretion out [1] of the cell
OR
Mitochondria [1]:
site of aerobic respiration where glucose is oxidised to release energy [1]
for cellular activities
OR
Rough Endoplasmic Reticulum [1]:
To transport proteins synthesised by ribosomes to the Golgi apparatus
for secretion out of the cell [1]
OR
Smooth Endoplasmic Reticulum [1]:
synthesises fats and steroids / convert harmful substances into
harmless substances via detoxification [1]

25
Q

Use a named example, describe the relationship between cells, tissue
and organ. [4]

A

The heart consists of different tissues to perform a specific function [1]
such as the muscle tissue, connective tissue, blood tissues and nerve tissues. [1] *any 3 example

These tissues are a group of similar cells that work together to perform a specific function. [1] Eg. muscle tissue contains similar muscle cells with which synchronize their contractions to bring about the contraction of the
tissue. [1]

OR
The leaf consists of different tissues to perform a specific function [1]
such as the palisade tissue, spongy mesophyll tissue, xylem tissues and
phloem tissues. [1] *any 3 examples
These tissues are a group of similar cells that work together to perform a specific function. [1] Eg. palisade tissue contains similar palisade
mesophyll cells with chloroplasts to trap sunlight to make glucose by
photosynthesis [1]

26
Q

Describe how the protein is synthesised and transported in the cell for secretion. [4]

A

Proteins made / synthesised by the ribosomes on the rough endoplasmic reticulum (RER) enter into RER. [1]
The manufactured proteins are transported in vesicles that are pinched off from the RER and are transported to the Golgi apparatus. [1]

The Golgi apparatus stores and chemically modifies the proteins made by
RER and packages them into vesicles. [1]

The secretory vesicles containing the modified proteins are pinched off from the Golgi apparatus. The vesicles then move to the cell membrane and fuse with the membrane. This releases the contents in the vesicles into the
outside of the cell. [1]

27
Q

How does the cell wall help to maintain turgor of a plant cell?

A

It supports the cell membrane.

28
Q

What structures are involved in enzyme synthesis in a cell?

A

Ribosomes on RER
Nucleus (contains genetic info that codes for enzyme)
Mitochondria (proves energy to manufacture enzyme)
Golgi apparatus (modifies, sorts and packages)

29
Q

Suggest why liver cells have many mitochondria. [2]

A

The mitochondrion is the site of aerobic respiration where chemical energy in the form of ATP is released. There are large numbers of mitochondria in liver cells to release the energy needed to carry out metabolic reactions, for example protein synthesis.