BIOH122 Human Biological Science

BIOH111/BIOH1Human Biological Science 1

Final Exam Workshop Series

1. Cell Biology

Friday 27th Aug 2021

Sara Zangana

ResourcesLibrary LibGuides > Bioscience > Human Biological Science

Prescribed reading: Principles of Anatomy & Physiology. Tortora et al. 2018 2nd Asia-Pacific Edition. Chapter 3: The cellular level of organisation

Essentials of Human Anatomy & Physiology. Marieb & Keller, 2017. Chapter 3. Cells and Tissues.

Cells are the single organisational unit in the body. We have trillions of them, and they come in different shapes and sizes-depending on their role.

Some move freely around body, connect body parts, line organs, store nutrients, fight disease, gather information, control, fertilisation.

Encasing the cell is a plasma membrane and within is the cytoplasm that contains fluid (cytosol) and tiny factories called organelles.

You will learn about the generalised structure however note a certain cell in the body will be adapted with the type or amount of organelles e.g. a skeletal muscle cells has lots of mitochondria whereas the sperm cell is the only to have a flagellum!

Marieb page 101

1. Within the cytoplasm are tiny structures called organelles.

(10 marks)

I. Define organelles. (1 mark)1 sentence with two points on what an organelle is [3.1; pg 97]

II. Name THREE (3) organelles. (3 marks)List any three (1 mark each). Note- NOT the plasma membrane or

cytoplasm [3.4; pg 119-131]

III. Describe the structure of each of the organelles. (3

marks)For each give it’s defining features i.e. what is it made up of/ how is it

shaped (1 mark each) [Table 3.2; pg 135]

IV. Describe 1 function for each of the organelles. (3 marks)For each give it’s function in a few words (1 mark each). E.g. the

mitochondria makes energy (ATP) through aerobic respiration rather

than it’s the ‘powerhouse’ of the cell [Table 3.2; pg 135]

Tortora pg 96

MariebTable 3.1 page 98

What determines HOW a cell works?

GENE EXPRESSION

DNA: the basic building block of chemicals that makes youi.e. the blueprint that codes for the proteins to be made in a cellA stretch of DNA that codes for a particular protein = GENE

http://www.cancermoonshotlund.com/

Somatic cells have 46 chromosomes (23 pairs)Gametes have 23 chromosomes

2. Central dogma describes the process of gene expression.

(10 marks)

I. Define gene expression. (1 mark)Process by which information from a stretch of DNA is used as a template

for the synthesis of a specific protein [3.6 pg 136]

II. Name the two (2) cellular processes involved in gene

expression in the order they occur. (2.5 marks)Transcription > Translation

III. Define each of these two (2) processes. (2.5 marks)1. Transcription uses DNA to create a copy in the form of mRNA

2. Translation uses mRNA to code for the type and order of amino acids

joined together to make the protein

IV. Each of these processes has three (3) steps. List the three

(3) steps that happen in both in the correct order.

(4 marks)1. Initiation

2. Elongation

3. Termination

Chemical structure of one DNA nucleotide

Marieb Fig 2.21 pg 79

DNA

Tortora Fig. 3.26 pg 137

Did you know….

The human genome contains some 30,000 genes yet there are 500,000 to 1 million human proteins


Alternative splicing! More than 1 mRNA can be made form same DNA


1. Transcription of DNA to RNA by RNA polymerase

The RNA is single stranded

2. Translation of RNA to protein

mRNA

tRNA

IV. Each of these processes has three (3) steps. List

the three (3) steps that happen in both in the correct

order.

(4 marks)

Transcription1. Initiation: RNA polymerase binds to piece of DNA and causes it to

unwind

2. Elongation: Addition of nucleotides to make RNA

3. Termination: complete RNA formation, detachment from DNA

Translation1. Initiation: mRNA binds to ribosome ‘start codon’

2. Elongation: Addition of amino acids to make protein

3. Termination: complete protein formation, detachment from

ribosome

Where do the synthesised proteins go and what do they do?

Where do the synthesised proteins go and what do they do?

https://www.nature.com/

http://e.hormone.tulane.edu/learning/types-of-hormones.html

https://www.news-medical.net/health/Insulins-role-in-the-human-body.aspx

Cell structureTransportationCommunication

3. Glucose levels in the blood are tightly regulated by

transporters present on the plasma membranes of the cell.

Because of this tight regulation the cell uses two transport

mechanisms that allow glucose to enter the cell – facilitated

diffusion and active transport. (10 marks)

I. Define the process of facilitated diffusion. (2.5 marks)1. Does it use energy? (passive or active). NO ATP

2. How is it facilitated? (channel and carrier proteins which are integral

proteins).

3. How does it rely on concentration gradients? Down the concentration

gradient.

II. Explain in detail how glucose moves across the membrane

utilising facilitated diffusion. (2.5 marks)Use points above in the context of glucose specifically i.e. how does it

cross a cell membrane, explaining the integral protein (carrier) and how it

moves down the concentration gradient.

Tortora pg 107II.

3. Glucose levels in the blood are tightly regulated by

transporters present on the plasma membranes of the cell.

Because of this tight regulation the cell uses two transport

mechanisms that allow glucose to enter the cell – facilitated

diffusion and active transport. (10 marks)

III. Define the process of active transport. (2.5 marks)1. Does it use energy? (Uses ATP)

2. Uses a carrier protein- what are the two types? We have either primary

(using pumps) or secondary active transport (symporters or

antiporters).

3. How does it rely on concentration gradients? Substance moves from a

lower to higher concentration (against).

IV. Explain in detail how glucose moves across the membrane

utilising active transport. (2.5 marks)

1. Primary active transport

2. Secondary active transport

How does glucose enter the cell using secondary active transport?Relate this to theelectrochemical gradient ofNa+ established by primaryactive transport first.

Na+/glucose symporter

Sodium kicked out cell

Firstly, in primary active transport, ATP is used to push Na+ out of the cell against its concentration gradient. A lot of Na+ builds up outside of the cell.Then the Na+/glucose symporterprotein allows Na+ back into the cell down it’s gradient and glucose enters the cell at the same time.

4. Cell regulates molecule concentration across the membrane

by using active transport processes, carrier proteins and ion

channels. (10 marks)

1. Define the process of active transport. (2.5 marks)1. Does it use energy? (passive or active?)

2. Uses a carrier protein- what are the two types?

3. How does it rely on concentration gradients?

II. Define secondary active transport. (2.5 marks)Energy stored in the ion gradients e.g. Na+ in primary active transport

drives substance movement in secondary active transport. What are the

two carriers used?

III. Describe how glucose is actively transported across the

cell membrane. (2.5 marks)Discuss the Na+/glucose symporter movement

IV. Describe how calcium is actively transported across the cell

membrane. (2.5 marks)Discuss Na+/Ca2+ antiporter movement

1. Primary active transport

2. Secondary active transport

How does glucose enter the cell using secondary active transport?Relate this to theelectrochemical gradient ofNa+ established by primaryactive transport first.

Na+/Ca2+ antiporter

Sodium kicked out cell

Some proteins are involved in cell division:

Mitosis- process by which somatic cells produce identical copies of themselves i.e. 1 parent cell > 2 x identical daughter cells

Meiosis- process by which reproductive cells produce non-identical cells i.e. 1 parent cell > 4 x non-identical daughter cells

https://pharmaceuticalintelligence.com/

Tortora pg 143

5. The cell cycle is a series of events that occurs in a somatic

cell to produce two daughter cells and includes

interphase, nuclear (mitosis) and cytoplasmic (cytokinesis)

division. (10 marks)

I. Describe in detail ONE (1) event that occurs during

interphase (1 mark)

Pick one from the purple zone e.g. DNA replication where a

copy of the DNA is made

II. Identify the FOUR (4) phases of mitosis, in the correct order

of occurrence (5 marks)

Prophase > Metaphase > Anaphase > Telophase

III. Describe at least 1 event that occurs in each phase (4

marks)

Pass Me Another Tea

III. Describe at least 1 event that occurs in each phase (4 marks)

Tortora pg 134

2 m long!

DNA in a non-diving cell

DNA in a diving cell

Tortora pg 145

Interphase- before mitosis

Cell grows and the nuclear DNA is duplicated

Prophase• chromatin fibres condense and shorten into chromosomes • formation of mitotic spindle • centrosomes to poles of cells • nucleolus and nuclear envelope disappear

Metaphase• chromatid pairs align at the centre of mitotic spindle (metaphase plate)

Anaphase• chromatids separated and move to opposite poles of cell and appearance of cleavage furrow

Telophase• chromosome uncoil and revert to threadlike chromatin • formation of nuclear envelope and reappearance of nucleoli • mitotic spindle breaks up

After mitosisNew identical cells in interphase

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BIOH122 Human Biological Science