Production of unspecialized cells following fertilization and their development into specialized cells by differentiation
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All 23 Flashcards — Production of unspecialized cells following fertilization and their development into specialized cells by differentiation
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Question
What is differentiation?
Answer
The process by which an **unspecialized cell becomes a specialized cell** with a particular structure and function.
Question
What is an unspecialized cell?
Answer
A cell that has **no particular job yet** and can still develop into different cell types (e.g. a stem cell).
Question
Do all body cells of an organism have the same genome?
Answer
**Yes** — every body cell carries the same complete set of genes (the same genome).
Question
If the genome is the same in every cell, what makes cell types differ?
Answer
**Different genes are expressed** (switched on) in each cell type — not different genes present.
Question
What is a specialized cell?
Answer
A cell with a **particular structure suited to one particular function** (e.g. a neuron or red blood cell).
Question
What is gene expression?
Answer
Switching a gene **'on'** so it is used to make its **protein**. An expressed gene is active; an unexpressed gene is silent.
Question
Name the process that produces specialized cells such as neurons from unspecialized cells.
Answer
**Differentiation**.
Question
What is selective gene expression?
Answer
Expressing **only some** of the genes in the genome — different genes in different cell types — so each cell makes only the proteins it needs.
Question
What process is required to develop specialized tissues in a multicellular organism?
Answer
**Differentiation** — it produces the specialized cell types that group into tissues.
Question
What tells a cell which genes to switch on during development?
Answer
**Chemical signal gradients** — the concentration of signalling molecule a cell meets depends on its **position**.
Question
How does cell division differ from differentiation?
Answer
**Cell division (mitosis)** makes **more** cells (identical copies); **differentiation** makes cells **different** (specialized).
Question
Which process increases the NUMBER of cells?
Answer
**Cell division (mitosis)** — it makes more identical cells.
Question
What is a concentration gradient of a signal?
Answer
A smooth change in the concentration of a signalling molecule — **high near its source**, lower further away.
Question
Which process increases the VARIETY of cell types?
Answer
**Differentiation** — it makes cells become different from one another.
Question
How does position in a gradient affect a cell?
Answer
A cell's **position** sets the **signal concentration** it meets, which switches on a **particular set of genes**, deciding the cell type it becomes.
Question
In what order do division and differentiation build a body?
Answer
First **cell division** makes many identical cells, then **differentiation** makes them into specialized types.
Question
What is the outcome when an unspecialized cell meets a signal gradient?
Answer
It **differentiates** — switching on specific genes and becoming a specialized cell type.
Question
Why do expressed genes make a cell specialized?
Answer
The genes switched on are used to make **specific proteins**, which give the cell its specialized **structure and function**.
Question
Why does a multicellular organism need differentiation?
Answer
So cells can **specialize for one job each** (division of labour), letting the whole organism do many jobs efficiently.
Question
Are genes deleted from a cell when it differentiates?
Answer
**No** — unused genes are switched **off**, not removed. The cell keeps the full genome.
Question
Where does the word 'differentiation' come from?
Answer
From **'different'** — it makes cells become **different from one another** (specialized).
Question
State the cause-and-effect chain of differentiation.
Answer
Position in gradient → **signal concentration** detected → **genes** switched on → **proteins** made → specialized **cell type**.
Question
Do all the specialized cells in one organism contain the same genes?
Answer
**Yes** — they all came from the same original cell and share the same genes, but they differentiated into different types.
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Cell specialization
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